Flight Level 31,000'!

Geico266

Geico266

Touchdown! Greaser!
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Geico
As I touched down at my home airport after a two day trip I was handed a note from the line dude that I needed to call Center. YIKES! I was ferrying from Portland to Nebraska VFR in a "new" plane.

What did I do wrong now? :yikes:

So I called. Seems the transponder / encoder was not working properly. When I switched it to ALT it was reporting me to center at 31,000'! :yikes: For 2 days! :yikes: They tried to call Gillete, WY FBO & tower, but no one was there except me. So this AM I fueled up and left and turned everything on again and :yikes: ,,, The poor guy sitting at the radar screen at Center sees me at 31,000 feet again. :mad2:

They asked what kind of plane I was flying and when I assured them I was not at 31K MSL they asked me to please have someone look at the transponder. Roger, Wilco, Out!

Interesting lesson learned here!
 
thats nice that they got ahold of you. it really screws up the high altitude sectors when this sort of thing happens.
 
tonycondon said:
thats nice that they got ahold of you. it really screws up the high altitude sectors when this sort of thing happens.
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I really felt bad! I can only imagine the heart burn I was causing! I can only imagine the poor controllers having to deal with this.
 
What was your ground speed and when did you activate Mode C? Seems like even the dimmest of bulbs could have figured it out pretty quick. I'm guessing they did and that it didn't cause them much heartburn.

But now look at the mess you made for the rest of us. TSA will be all over us like a cheap suit, claiming a threat to the safety of airline ops. What a klutz!:rofl:

look what you've
Geico266 said:
I really felt bad! I can only imagine the heart burn I was causing! I can only imagine the poor controllers having to deal with this.
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wabower said:
What was your ground speed and when did you activate Mode C? Seems like even the dimmest of bulbs could have figured it out pretty quick. I'm guessing they did and that it didn't cause them much heartburn.
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I would bet that even if they "know" that the plane isn't really at 31,000 feet that they're still not allowed to clear any airplanes through the same space.
 
Wow, FL310, and not even RVSM compliant! You've got some 'splainin to do!.
 
It happened to me when my altitude encoder failed and Chicago saw me in the flight levels on the lakefront VFR route. Amazingly, that time they wanted to talk to me. Meigs tower asked me to verify (twice) and told me to stop squawking altitude.

Now of course, (then too, really) they don't answer us so they can just deal with it.

A hint: the altitude encoder to transponder link is octal 7-bits, so a bit flipping would toggle 8,64,512,4096,32768 feet

Oh, and FL 31000 would be 310,000 feet which is up with the Space Shuttle and low earth orbit satellites. :rolleyes:
 
I wonder if they called that 'target' out at all to anyone?
Ha: "SW243, unknown traffic 12 oclock 10miles reporting same altitude you are overtaking by 300kts let me know if you see him"
 
Henning said:
I thought FL 31000 would be 3,100,000'
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OK.

My calculator tells me that 22000 miles up where geosync sats are is 116,160,000 feet. I gotta guess that 3,000,000 feet is orbit altitude. I ain't in the mood to google vs. guess. :rolleyes:
 
When I used to work in an avionics shop we had someone come in with the same kind of problem. I also ferried a plane that kept showing an altitude to ATC that was a few hundred feet off. Every time I checked in, I had to convince ATC that I had the right altimeter setting and assure them the plane would get checked out ASAP.
 
Heck, I remember one time I was sitting in the FBO when Center called and asked them to tell the plane that just landed (inside the 30NM Mode-C veil of O'Hare) that his xpdr was squaking FL 600 as he LANDED! Obviously they knew that it was an erroneous xpdr. Of course, I run down the taxiway, notify the pilot of the Aerobat II, and get offered a flight! Who am I to say no? A faulty xpdr is his problem, not mine!:rofl:
 
I was flying a 182 one day, and ATC showed me several thousand feet higher than I was..."stop altitude squawk". Okee-dokee.

Couple of sectors later, I asked if I could give it a try...it was dead-on. Let 'er run.

Then, showed high. Then, showed dead-on.

I happened to look at the altitude readout on the transponder as I was pulling cabin heat once...Boy, did that sucker climb FAST! Turns out, the static line to the encoder ran right past the heat duct, melted, and got all that nice, hot, high-density-altitude air to the encoder when I turned on the heat.:eek:
 
MauleSkinner said:
I was flying a 182 one day, and ATC showed me several thousand feet higher than I was..."stop altitude squawk". Okee-dokee.

Couple of sectors later, I asked if I could give it a try...it was dead-on. Let 'er run.

Then, showed high. Then, showed dead-on.

I happened to look at the altitude readout on the transponder as I was pulling cabin heat once...Boy, did that sucker climb FAST! Turns out, the static line to the encoder ran right past the heat duct, melted, and got all that nice, hot, high-density-altitude air to the encoder when I turned on the heat.:eek:
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Obviously something involving the heat was casusing your problem but not density altitude, the encoder responds to pressure only and the pressure in your cabin doesn't change with temperature.
 
gismo said:
Obviously something involving the heat was casusing your problem but not density altitude, the encoder responds to pressure only and the pressure in your cabin doesn't change with temperature.
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The heat could increase the pressure--but in an open environment like that--it'll just balance out--I don't see how it could raise it to any measurable level.
 
jpflys said:
You never used FF or talked to any center?
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Radar coverage out that way is spotty at best. For the brief bit where I filed IFR on my trip out there, Denver Center couldn't see me at 12,000 feet. SLC Center eventually picked me up.
 
jesse said:
The heat could increase the pressure--but in an open environment like that--it'll just balance out--I don't see how it could raise it to any measurable level.
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From my very rudimentary understanding of encoders, don't they have a fan of some kind inside which regulates the temperature? If the fan is broken, the encoder could heat up a lot with the engine heat behind the firewall and show an erroneous reading.
 
The encoder was wired wrong. Switched a wire and it works fine on the bench. We'll test it out tomorrow with ATC weather permitting.
 
Geico266 said:
The encoder was wired wrong. Switched a wire and it works fine on the bench. We'll test it out tomorrow with ATC weather permitting.
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A lead permanently switched to the wrong point gives an intermittent error? :confused:
 
Greg Bockelman said:
Who said it was intermittent?
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Oops, I got that impression. But, I may have combined more than one post in my mind. Going back, it sounds like he never used Mode C.

I can't imagine flying without it if so equipped. Even if you're not talking to anyone, it sure helps keeping some away from ya if the controller can see your altitude.
 
jesse said:
The heat could increase the pressure--but in an open environment like that--it'll just balance out--I don't see how it could raise it to any measurable level.
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The output frequency of oscillators is usually temperature-dependent, and that can affect the accuracy of its output. I suspect encoders use oven-controlled crystal oscillators, that include a heater designed to warm the oscillator to about 10 degrees above the highest expected value.

I've got a Microair transponder with altitude readout, and I noticed that it takes longer for the encoder to start providing altitude when the weather is cold. I suspect there's a warm-up time for the oscillator, and the encoder doesn't produce an output until the temperature is above a certain point. The original encoder took 5-10 minutes to warm up in cold weather, but the new one takes a maximum of about 30 seconds.

Warming the oscillator above its normal operating range will make it run a bit faster. Eventually, some aspect of the performance is undoubtedly going to be affected.

Oh, and as far as using FF or talking to center... I never have, in 37 years of flying. Haven't talked to a standard control tower in about ten years (though I talk to a temporary tower when I go into the Arlington Fly-In).

Ron Wanttaja
 
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Keep in mind that even if the controller "knows" you aren't at FL310, the ATC computer isn't so smart, and will trigger all sorts of alarms. It must have been driving ARTCC's crazy all the way home.
 
Ron Levy said:
Keep in mind that even if the controller "knows" you aren't at FL310, the ATC computer isn't so smart, and will trigger all sorts of alarms. It must have been driving ARTCC's crazy all the way home.
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And causing TCAS RAs
 
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