Navaho Ambulance down short of PWK

[Ted]

If you fly in the winter a lot in a light twin with a gas-powered heater, you can expect your tanks to become unbalanced because the heater will draw fuel from one tank and so the drain on that tank is higher. To compensate, the pilot will crossfeed the engine from the other tank for a bit (maybe 10 minutes out of an hour) so that the drain from both tanks matches up.

In none of the twins I fly have I had to do that. When you're looking at an addition of ~1 GPH for the combustion heater vs. the 20-40 gph the plane is burning otherwise, it's pretty much irrelevant.

Well, this plane was used for revenue service. It would be reasonable to expect that such a plane has a digital fuel flow gauge and a fuel totalizer. Unfortunately, some operators seem to work under the premise that the fewer pieces of equipment they install in their revenue plane, the fewer things can break and they are generally cheap, also there is no FAR that requires an operator to be 'reasonable'.

Your second half of the paragraph is more accurate. A revenue airplane has what it needs to do the job, typically.

 

[TMetzinger]

Ted,

1 GPH for a heater is insignificant. Someone quoted 3 GPH, which might be different.

Anyway, I got into this discussion because it appeared that a statement was made that a single fuel leak caused a unexpected dual engine failure. I tried to explain why that wasn't a logical conclusion based on the way that twin fuel systems work.

As for the rest of it, I still don't think a pilot who does what he's supposed to do whould ever be surprised to run out of fuel. He may run out of fuel if he develops a leak and cannot make it to a refueling point, but he should detect it and be ready for a shutdown.

Edit: I almost ran out of fuel today.
In my car.
And I was ready for it (driving in the right lane, etc) until I got to the gas station. Looks like I had a half-gallon remaining.

 

[Ted]

1 GPH for a heater is insignificant. Someone quoted 3 GPH, which might be different.

I'd suspect it to size upwards with the engine size, and thus the fuel consumption. My Aztec's quoted at 1 GPH. I forget what the Navajo book said on it. It probably is a bit higher, maybe 3 gph. The Navajo also burns twice the fuel of my Aztec. Point is, I've never been told and never known anyone who tries to balance out the fuel left to right for the combustion heater. That seems to me to be overthinking things, and a good way to cause more problems.

Anyway, I got into this discussion because it appeared that a statement was made that a single fuel leak caused a unexpected dual engine failure. I tried to explain why that wasn't a logical conclusion based on the way that twin fuel systems work.

If a leak was undetected at all, that is probably correct.

As for the rest of it, I still don't think a pilot who does what he's supposed to do whould ever be surprised to run out of fuel. He may run out of fuel if he develops a leak and cannot make it to a refueling point, but he should detect it and be ready for a shutdown.

Which may very well have happened.

A double engine failure in a Navajo would be a really bad day. Even with both turning, they tend to have a descent profile roughly equivalent to a Steinway. Wayne outlined a very plausible situation.

 

[weilke]

The timing of the fracture, the pilot's awareness of the situation and his ability to properly diagnose the problem (IMO almost impossible) were contributing factors to the resulting accidents or (in my situation) a forced landing at an unintended airport along the route of flight.

You ran out of fuel !

You are obviously an idiot who doesn't know what he is talking about and unfit to pilot anything more than maybe a childrens kite .

Before we throw the guy with the Navajo under the bus, I would like to know whether this ship had locker tanks (many do). 3 days earlier he flew a 3:37 leg without falling out of the sky, who knows, transfer valve clogged, fuel leaked overbord any number of things. Sure, maybe he was an idiot and cut it too close, we just don't know that for a fact.

 

[Ted]

Before we throw the guy with the Navajo under the bus, I would like to know whether this ship had locker tanks (many do). 3 days earlier he flew a 3:37 leg without falling out of the sky, who knows, transfer valve clogged, fuel leaked overbord any number of things. Sure, maybe he was an idiot and cut it too close, we just don't know that for a fact.

With full fuel, I typically plan for 4 hours 30 minutes of flight time in the Navajo. At 40 gph average in the 310 HP version, I should have about 4:45, in the Chieftain about 4:30 on the dot.

It is suspicious that he had such a short leg before that long leg as far as fuel goes, but we don't know for sure. I am even more careful with taking on partial fuel and relying on tailwinds, simply because with partial fuel it's hard to know exactly how much you have (unless you do something like fill the inboards) and tailwinds usually aren't as good as advertised.

 

[Everskyward]

Anyway, I got into this discussion because it appeared that a statement was made that a single fuel leak caused a unexpected dual engine failure. I tried to explain why that wasn't a logical conclusion based on the way that twin fuel systems work.

That might be true if they didn't notice the imbalance at all, but the hypothesis is that they did notice and tried to correct it with crossfeed. The problem would be that if the leak was from the line leading to the engine and not the tank it would still be leaking when they switched to the other tank.

They will probably be able to find out what happened in this case because one of the pilots survived but that's one way it could have happened.

As for the rest of it, I still don't think a pilot who does what he's supposed to do whould ever be surprised to run out of fuel. He may run out of fuel if he develops a leak and cannot make it to a refueling point, but he should detect it and be ready for a shutdown.

But the normal reaction to a fuel imbalance in a twin is to crossfeed not to run one side dry if for no other reason that the airplane will become very wing heavy. Many airplanes have a limitation on how far out of balance they can be, or at least how much has been demonstrated. I have no idea about the Navajo. In the hypothetical situation they would have been burning and losing more fuel than normal no matter which tank(s) were selected.

 

[TMetzinger]

You ran out of fuel !

You are obviously an idiot who doesn't know what he is talking about and unfit to pilot anything more than maybe a childrens kite .

Before we throw the guy with the Navajo under the bus, I would like to know whether this ship had locker tanks (many do). 3 days earlier he flew a 3:37 leg without falling out of the sky, who knows, transfer valve clogged, fuel leaked overbord any number of things. Sure, maybe he was an idiot and cut it too close, we just don't know that for a fact.

I don't blame pilots for starvation (where there's fuel in the tanks but you can't get it to the engines) unless their actions caused it. Far too many exhaustion accidents are due to :

Pilots not monitoring their fuel usage and availability.
Pilots knowingly pressing on when they were low on fuel.

 

[bbchien]

There are so many issues here:
Maintenence: in a part 135 operation (fuel system and gauges).
Maintenence: fuel flow equpment (pressure differential indicators)
Standard operations under a part 135 certificate.
Squawk history of the systems
Power settings
Judgement of the pilot who had run the tanks down 167 gallons before!
Locker tanks and tank managment.
Combustion heater plumbing...

This one is gonna cause a lot of grief, as it should.
Unfortunately this situation is rather like saying "the anesthesiologist should have known". Sadly, he is the backstop to ALL the failings in the hospital. In this situation the pilot has to be really, really sage. Usually he's a 24 year old kid...who MIGHT be sage, but he might just NOT be sage.

 

[wabower]

We didn't run out, but didn't have much left.

You ran out of fuel !

You are obviously an idiot who doesn't know what he is talking about and unfit to pilot anything more than maybe a childrens kite .

Before we throw the guy with the Navajo under the bus, I would like to know whether this ship had locker tanks (many do). 3 days earlier he flew a 3:37 leg without falling out of the sky, who knows, transfer valve clogged, fuel leaked overbord any number of things. Sure, maybe he was an idiot and cut it too close, we just don't know that for a fact.

 

[yakshemash]

There are so many issues here:
Maintenence: in a part 135 operation (fuel system and gauges).
Maintenence: fuel flow equpment (pressure differential indicators)
Standard operations under a part 135 certificate.
Squawk history of the systems
Power settings
Judgement of the pilot who had run the tanks down 167 gallons before!
Locker tanks and tank managment.
Combustion heater plumbing...

This one is gonna cause a lot of grief, as it should.
Unfortunately this situation is rather like saying "the anesthesiologist should have known". Sadly, he is the backstop to ALL the failings in the hospital. In this situation the pilot has to be really, really sage. Usually he's a 24 year old kid...who MIGHT be sage, but he might just NOT be sage.

All very good points. No wing locker tanks on this bird. Also, the POH for this year PA-31 doesn't list fuel burn for the heater. They consider it negligible. I figure on at least one gal an hour for the heater from the right side, but NEVER had a significant fuel imbalance when using the heater.

 

[TMetzinger]

All very good points. No wing locker tanks on this bird. Also, the POH for this year PA-31 doesn't list fuel burn for the heater. They consider it negligible. I figure on at least one gal an hour for the heater from the right side, but NEVER had a significant fuel imbalance when using the heater.

My MEI must have just been an "overthinker". Or he wanted me to know how to use crossfeed to balance the fuel load in the event there was an imbalance.

 

[wabower]

Maybe he figured it was a good way to introduce the concept and teach the system, since the actual need for other purposes is so infrequent.

Fuel management discussions by big-watch-little-dick-pilots at the FBO provide interesting kibitzing opportunities. When you hear them yakking about the difficulties of managing tip-tank Cessna systems, you might assume the degree of difficulty is right up there with space ship re-entry.

If you understand the system and fly the airplanes, you know the total time required is less than 30 seconds per trip. Go figure.

My MEI must have just been an "overthinker". Or he wanted me to know how to use crossfeed to balance the fuel load in the event there was an imbalance.

 

[Ted]

Fuel management discussions by big-watch-little-dick-pilots at the FBO provide interesting kibitzing opportunities. When you hear them yakking about the difficulties of managing tip-tank Cessna systems, you might assume the degree of difficulty is right up there with space ship re-entry.

 

[yakshemash]

NTSB Identification: CEN12FA086
Nonscheduled 14 CFR Part 135: Air Taxi & Commuter
Accident occurred Monday, November 28, 2011 in Riverwoods, IL
Aircraft: PIPER PA-31-350, registration: N59773
Injuries: 3 Fatal,2 Serious.
This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.
On November 28, 2011, about 2250 central standard time, Lifeguard N59773, a Piper PA-31-350, an emergency medical services (EMS) flight, operated by Trans North Aviation Ltd, sustained substantial damage when it impacted trees and terrain in Riverwoods, Illinois. The pilot declared an emergency, reported that the airplane was out of fuel and the flight was coasting direct to the destination airport, Chicago Executive Airport (PWK), near Wheeling, Illinois. The airline transport pilot and two passengers sustained fatal injuries. The pilot-rated passenger and medical crewmember received serious injuries. The non-scheduled domestic on-demand passenger flight was conducted under 14 Code of Federal Regulations Part 135. Night visual meteorological conditions prevailed at the time of the accident. An activated instrument flight rules flight plan was on file. The flight departed from the Jesup-Wayne County Airport (JES), near Jesup, Georgia, about 1858.

Fueling records show an airplane was fueled at JES with 165 gallons of aviation gasoline (avgas).

Preliminary review of a recording of the approach controller’s frequency revealed that the pilot requested to fly direct to the outer marker navigation aid. The controller indicated a heading for the flight to conduct an instrument approach. The pilot then declared an emergency. The controller inquired if the flight was still heading to PWK. The pilot reported that he was unable, out of fuel, and that the airplane was “coasting.” The controller asked if the field was insight. The pilot reported negative and asked for the cloud tops. The controller indicated that the cloud deck was 1,400 feet overcast. The pilot responded that the flight was coasting down and that the pilot would report visual contact. The pilot further indicated that the flight was flying direct to PWK. The controller advised a low altitude alert and the flight acknowledged that alert. The controller asked if the pilot had the field in sight. The pilot reported affirmative. The flight was cleared for the visual approach to runway 16 and the pilot was informed to cancel the flight’s IFR flight plan. The controller further indicated that the change to airport’s advisory frequency was approved. There was no further recorded radio communication with the EMS flight.

The Riverwoods Police Department received an initial 911 phone call about 2250. The first responders found the wreckage near a residence northwest of the intersection or Portwine and Orange Brace roads.

The pilot held an airline transport certificate and he held a first-class medical certificate.

The pilot-rated passenger held a commercial pilot certificate and he held a second-class medical certificate

N59773, was a Piper PA-31-350, Chieftain, twin-engine, retractable landing gear, conventional semi-monocoque design airplane with serial number 31-7652044. The airplane had a maximum gross weight of 7,000 pounds. A 350-horsepower Lycoming TIO-540-J2BD engine and a 350-horsepower Lycoming LTIO-540-J2BD engine powered the airplane.

At 2252, the recorded weather at PWK was: Wind 350 degrees at 9 knots; visibility 10 statute miles; sky condition overcast 1,400 feet; temperature 2 degrees C; dew point -2 degrees C; altimeter 29.99 inches of mercury.

At 2352, the recorded weather at PWK was: Wind 360 degrees at 9 knots; visibility 10 statute miles; sky condition overcast 1,400 feet; temperature 2 degrees C; dew point -2 degrees C; altimeter 29.97 inches of mercury.

The airplane impacted trees and terrain in a heavily treed residential neighborhood about 3 nautical miles northeast of PWK. The wreckage path was about 250 feet in length from the first found impact tree to the main wreckage on a magnetic heading of about 130 degrees. The airplane was found fragmented along the path. The left propeller separated from its engine and was found 32 feet west of the main wreckage. The airplane fuselage came to rest facing about 280 degrees magnetic. An on-site inspection confirmed that the fuselage, empennage, wings, and all flight control surfaces were located within the wreckage debris path. The landing gear were found in the up position in their wheel wells.

The left and right throttle levers were found in the full forward position. Both left and right mixture levers were found in the forward rich position. The left and right propeller levers were found in the forward high RPM position. The Hobbs meter read 2848.8 hours. All four magneto switches were in the on position. The left fuel boost pump switch was in the on position and the right fuel boost pump switch was in the off position. Both the left and right fuel tank selectors were selecting their respective inboard fuel tanks. The crossfeed valve was found in the on position. All fuel caps were in place in their filler necks. Approximately 1.5 ounces of a liquid consistent with avgas was found within the airplane fuel system. All four electric fuel pumps were operational when electrical power was applied to them. The flap jackscrew was consistent with retracted flaps in the up position. Left and right engine control continuity was established. Flight control continuity was established.

Both engines’ crankshafts were rotated and each engine exhibited gear and valve train continuity. All cylinders produced thumb compression and suction. Both dual magnetos produced sparks at all leads. All removed sparkplugs exhibited the appearance of normal combustion. Both engines’ turbocharger impellers spun when rotated by hand. The left and right propellers were found in the feather position. Index for Nov2011 | Index of months

 

[flyingcheesehead]

The left and right throttle levers were found in the full forward position. Both left and right mixture levers were found in the forward rich position. The left and right propeller levers were found in the forward high RPM position. The Hobbs meter read 2848.8 hours. All four magneto switches were in the on position. The left fuel boost pump switch was in the on position and the right fuel boost pump switch was in the off position. Both the left and right fuel tank selectors were selecting their respective inboard fuel tanks. The crossfeed valve was found in the on position. All fuel caps were in place in their filler necks. Approximately 1.5 ounces of a liquid consistent with avgas was found within the airplane fuel system. All four electric fuel pumps were operational when electrical power was applied to them. The flap jackscrew was consistent with retracted flaps in the up position. Left and right engine control continuity was established. Flight control continuity was established.

Both engines’ crankshafts were rotated and each engine exhibited gear and valve train continuity. All cylinders produced thumb compression and suction. Both dual magnetos produced sparks at all leads. All removed sparkplugs exhibited the appearance of normal combustion. Both engines’ turbocharger impellers spun when rotated by hand. The left and right propellers were found in the feather position. Index for Nov2011 | Index of months

Hmmm. There goes the fuel cap theory.

Also, two other questions:

1) Prop levers were full forward but both props were feathered. Why would that be the case? I can think of several theories, but none of them make sense to me.

2) "Both the left and right fuel tank selectors were selecting their respective inboard fuel tanks. The crossfeed valve was found in the on position." How is the fuel system configured on a Navajo? I can't conceive of how a system would work that had a single crossfeed valve/switch that didn't specify a direction ("in the on position") and would still have both selectors on a particular tank on their side.

 

[Ted]

1) Prop levers were full forward but both props were feathered. Why would that be the case? I can think of several theories, but none of them make sense to me.

a) Engines lost oil pressure and props feathered
b) Props were feathered, engines shut off, and for some reason they pushed the levers forward again in the event they tried to do a restart
c) Props were actually in the full forward position, and when they hit the ground and stopped spinning they were at a fast enough speed that the lock pins didn't have a chance to keep the props in fine pitch, so they defaulted to feathered.

2) "Both the left and right fuel tank selectors were selecting their respective inboard fuel tanks. The crossfeed valve was found in the on position." How is the fuel system configured on a Navajo? I can't conceive of how a system would work that had a single crossfeed valve/switch that didn't specify a direction ("in the on position") and would still have both selectors on a particular tank on their side.

The Navajo and Aztec crossfeed systems both are simply "on" or "off." On the Navajo, there's a valve that exists connecting the two sides between the airframe pump and the engine pump (on the Chieftain, there are two airframe pumps, and I forget if it's after both of them). If both tanks have fuel, there might be some cross-flow, but it should still work fine. Of course, in this case, there was no fuel left and thus this wouldn't have helped. If one tank is empty, you'd need that side to be "off."

 

[bob_albertson]

1.5oz of fuel.... that's a lot less than the unusable amount. I wonder if the tanks were breached upon impact. Either way, 1.5 oz isn't enough to reach the pickups, that's for sure . I'm sure the prelim just didn't include something about a tank breach, I don't think there is a way to get the tanks below just a couple 3 or less GALLONS per side.

Bob

 

[flyingcheesehead]

a) Engines lost oil pressure and props feathered

That's certainly the most sensible explanation... And I suppose the pilot would have pushed both levers full forward when one engine failed to get full power from the other engine, and maybe the other engine failed before he got through the engine failure procedure. That would also explain the mixtures being full rich.

The Navajo and Aztec crossfeed systems both are simply "on" or "off." On the Navajo, there's a valve that exists connecting the two sides between the airframe pump and the engine pump (on the Chieftain, there are two airframe pumps, and I forget if it's after both of them). If both tanks have fuel, there might be some cross-flow, but it should still work fine. Of course, in this case, there was no fuel left and thus this wouldn't have helped. If one tank is empty, you'd need that side to be "off."

So... With crossfeed open and both sides having a tank selected, you don't really know what's going where? (IE, you could be sending a little bit one way or the other, but who knows which way?) I'm assuming that you'd normally be setting one side to "off" if you wanted to crossfeed then, and/or turn the opposite side's electric pump on?

 

[Ted]

That's certainly the most sensible explanation... And I suppose the pilot would have pushed both levers full forward when one engine failed to get full power from the other engine, and maybe the other engine failed before he got through the engine failure procedure. That would also explain the mixtures being full rich.

Not having been in the cockpit, I think if he was trying to revive the engines it was probably option c). A normal glide ratio in a Navajo is about 0. With windmilling props, it's probably -2.

So... With crossfeed open and both sides having a tank selected, you don't really know what's going where? (IE, you could be sending a little bit one way or the other, but who knows which way?) I'm assuming that you'd normally be setting one side to "off" if you wanted to crossfeed then, and/or turn the opposite side's electric pump on?

That is correct. Normally, you select one side to "off", crossfeed "on", other side on whichever tank you want it drawing out of.

 

[flyingcheesehead]

That is correct. Normally, you select one side to "off", crossfeed "on", other side on whichever tank you want it drawing out of.

Can you think of any reason why the tank selectors would both have been on the inboard tank but with the crossfeed on?

 

[Ted]

Can you think of any reason why the tank selectors would both have been on the inboard tank but with the crossfeed on?

I know that if I had a double engine failure on the Navajo, even if it was solo, I would need new shorts. Doubly so if there were the lives of other people at risk. Dealing with the Steinway-esque glide ratio of a Navajo with two windmilling propellers would likely not give a tremendous amount of extra workload for properly diagnosing the problem correctly (of course, if you have 0 fuel on board, you will inevitably come to the conclusion that you're out of luck).

Pilot error comes to mind due to task saturation, potentially combined with a misunderstanding of the system.

 

[wabower]

The first question is whether it ran out fuel when it should have (range/endurance question) or before it should have (mechanical or pilot problem). Do we know the answer to that question?

Can you think of any reason why the tank selectors would both have been on the inboard tank but with the crossfeed on?

 

[Inverted]

Can you think of any reason why the tank selectors would both have been on the inboard tank but with the crossfeed on?

For all we know he could have been flying with the cross feed on the entire flight.

 

[Everskyward]

Just read an article on this in B&CA reproduced here.

http://www.aviationweek.com/Article.aspx?id=/article-xml/BC_03_01_2013_p55-541606.xml&p=1

The flight plan logs showed that the 182 gal. of usable fuel available for the Piper Chieftain should have been sufficient for all flight legs that day. The final accident leg from JES to PWK would have required the most fuel. FltPlan.com calculations assumed a fuel burn rate between 34-37 gph for cruise and the operating manual indicated a fuel burn between 26-35 gph (depending on the power setting) with the engines leaned to best economy. The average actual fuel burn computed for the flight legs flown on Nov. 28, 2011, was 47 gph.

Fuel records recovered from the wreckage indicated that the airplane was filled to its capacity with fuel at CFJ, PXE and at JES. The fuel records also indicated that only 75 gal. of fuel were added at PBI. A nominal fuel burn rate of 30 gph would indicate that landing with a minimum of 22.5 gal. of fuel would meet the 45-min. IFR fuel reserve requirement: With the Chieftain's 182 gal. of usable fuel, the maximum amount of fuel that should be added after a flight conducted under instrument flight rules is 159.5 gal. N59773 was serviced with 167.3 gal. and 165.0 gal. at PXE and JES, respectively.

I guess they are trying to say that the actual fuel burn for this airplane on this flight was more than the planned fuel burn. That's why they put more fuel in at the intermediate stops than would have been expected considering IFR reserves.

 

[Ted]

I wonder if the writers ever flew a Navajo. We burned 36-40 GPH on the -310 and 40-50 GPH on the Chieftain. It certainly could do better, but most Navajo operators I've talked to don't.

 

[N801BH]

I wonder if the writers ever flew a Navajo. We burned 36-40 GPH on the -310 and 40-50 GPH on the Chieftain. It certainly could do better, but most Navajo operators I've talked to don't.

I will trust Ted on those facts....

 

[weilke]

Not good:


The FAA Civil Aerospace Medical Institute prepared a Final Forensic Toxicology Accident Report on toxicological samples taken during the autopsy on the pilot. The report, in part, stated:

Blood unsuitable for analysis of Tetrahydrocannabinol (Marihuana)
0.1077 (ug/ml, ug/g) Tetrahydrocannabinol (Marihuana) detected in
Liver
0.0198 (ug/ml, ug/g) Tetrahydrocannabinol (Marihuana) detected in
Lung
0.0157 (ug/ml, ug/g) Tetrahydrocannabinol Carboxylic Acid (Marihuana)
detected in Liver
0.0024 (ug/ml, ug/g) Tetrahydrocannabinol Carboxylic Acid (Marihuana)
detected in Blood

Also, they started their day at 0700 and crasched at 2250. That's a long day.

Didn't notice any mention of a fuel totalizer in the description of the aircraft. Somehow they ended up burning more fuel than planned, unless it leaks before the transducer, a fuel-flow instrument should have picked that up.

CEN12FA086

 

[Everskyward]

I wonder if the writers ever flew a Navajo. We burned 36-40 GPH on the -310 and 40-50 GPH on the Chieftain. It certainly could do better, but most Navajo operators I've talked to don't.

The writers weren't the ones who came up with those numbers. The investigators recreated the flight planning from fltplan.com which is what the pilot used.

The passenger-pilot said that the senior pilot had done all the flight planning for the trip. Investigators could not locate the original flight planning records but were able to re-create the navigation logs in consultation with FltPlan.com — the resource used by the pilot for his planning.

 

[N801BH]

Not good:


The FAA Civil Aerospace Medical Institute prepared a Final Forensic Toxicology Accident Report on toxicological samples taken during the autopsy on the pilot. The report, in part, stated:

Blood unsuitable for analysis of Tetrahydrocannabinol (Marihuana)
0.1077 (ug/ml, ug/g) Tetrahydrocannabinol (Marihuana) detected in
Liver
0.0198 (ug/ml, ug/g) Tetrahydrocannabinol (Marihuana) detected in
Lung
0.0157 (ug/ml, ug/g) Tetrahydrocannabinol Carboxylic Acid (Marihuana)
detected in Liver
0.0024 (ug/ml, ug/g) Tetrahydrocannabinol Carboxylic Acid (Marihuana)
detected in Blood

Also, they started their day at 0700 and crasched at 2250. That's a long day.

Didn't notice any mention of a fuel totalizer in the description of the aircraft. Somehow they ended up burning more fuel than planned, unless it leaks before the transducer, a fuel-flow instrument should have picked that up.

CEN12FA086

With those THC levels I would assume you either got really toasted the night before or was smoking pot during the flight......

It has been awhile but wasn't there a survivor of that crash ?

 

[weilke]

With those THC levels I would assume you either got really toasted the night before or was smoking pot during the flight......

THC dissolves in fat and stays around for a long time. To me, the presence of THC is more of an indication of 'bad judgement' than necessarily pharmacological impairment. This pilot had a past history of two known DUIs, again pointing to a problem in the judgement arena.

 

[N801BH]

......history of two known DUIs, again pointing to a problem in the judgement arena.

I rest my case........................

 

[Ted]

The writers weren't the ones who came up with those numbers. The investigators recreated the flight planning from fltplan.com which is what the pilot used.

Understood, my point was that the numbers used aren't realistic from Navajo operators I've dealt with. I understand that assumptions were made, and so they took assumptions based on data they had. Probably took the hours that FltPlan.com had stated and then something from the manual regarding fuel burn.

Of course, we know that what manuals state and what pilots actually fly in the piston world aren't always the same.

 

[Everskyward]

Understood, my point was that the numbers used aren't realistic from Navajo operators I've dealt with. I understand that assumptions were made, and so they took assumptions based on data they had. Probably took the hours that FltPlan.com had stated and then something from the manual regarding fuel burn.

Of course, we know that what manuals state and what pilots actually fly in the piston world aren't always the same.

True, but either the pilot did not fly this airplane much and was not aware of its fuel burn, or was used to pushing it as he did on the other legs of the trip where he landed without IFR reserves based on the amount of fuel purchased at the destinations. In any case it seems that his assumptions about what the airplane was going to burn were incorrect.

 

[Ted]

True, but either the pilot did not fly this airplane much and was not aware of its fuel burn, or was used to pushing it as he did on the other legs of the trip where he landed without IFR reserves based on the amount of fuel purchased at the destinations. In any case it seems that his assumptions about what the airplane was going to burn were incorrect.

All of those are certainly possibilities. As I think was discussed earlier (I'm not going to re-read all the posts to confirm), Navajo fuel flow gauges and fuel level gauges are often not that accurate. Combine that with a tendency for pushing fuel...

 

[Skylane81E]

Let's just say there is a reason for 192 usable gallons of fuel...

We loaf ours along and still burn 34 combined

 

[Ted]

Interesting tidbit: the Navajo POH best economy numbers are LOP...

 

[weilke]

Interesting tidbit: the Navajo POH best economy numbers are LOP...

So are all Lycoming engine best economy numbers if one follows the companies directions.