When to slow to approach speed

I thought I had seen some discussion on this but nothing showed up in a search....

I've had my IR for a couple of years now. When I first started using it I would slow to
approach speed after passing the IAF so I wouldn't get behind the airplane (as much anyway).
Now it seems like I'm just dragging it in between the IAF and the FAF. I also don't like knowing
other IFR flights might be waiting on me before they can depart or start their approach. I was wondering if there was a general rule on when you slowed to approach speed and why.

 

I usually start slowing exactly halfway between IAF and FAF

 

Can’t worry about the planes behind you. But if you feel comfortable staying faster longer, go for it.

 

Every situation is different.

 

^^^yeah that. as long as I'm within gear speed just prior to the faf (without having to rush to get there) then I'm good with that.

 

Please to explain this. Time? Distance? Huh? I really enjoy "exactly" in your answer. Better than "precisely", but equally unattainable.

 

Whatever you are comfortable with prior to the FAF. As a new instrument pilot, I recommend slowing down early to be able to stay ahead of the airplane, but as you gain experience and comfort with the aircraft you can carry the speed a little further into the approach.

 

General Rule? Like in the AIM, Instrument Flight Procedures Handbook, Machado, etc. etc. I dunno. I think you have hit on a great General Rule on your own. Soon enough to have a safe Approach. Yeah, it’s nice to be mindful of the traffic behind you and not slow unnecessarily, but NEVER be pressured to exceed your comfort boundaries.

 

Flying slow translates into more time, which is the most valuable quantity during an approach. You can increase speed as you get more comfortable.

 

My instructor during IR taught me to slow to approach speed about 30-45 seconds prior to the FAF.. this seems to make sense and works well for me.. and covers a wide range of speeds, IE.. 30 seconds in a PA-28-140 is a much different distance figure than 30 seconds in a fast airplane.. your Moonies, etc.

..it does. But I have sat right seat for people who hone in on the CDI and next thing you know we're at 72 knots several miles out. Plus, if someone plans to fly real IMC instrument approaches there's a good chance any traffic around you will be faster, like PC-12, TBM, jets, etc. If someone gets used to droning in at 75 knots they'll either vector you way around, or potentially risk pushing you out of your element

Granted, for many trainers there isn't too much a wide range in speeds. The Warrior I did my PPL on cruised at something like 103 knots.. so I mean.. slowing to "90" or "85" for the approach is a fairly mundane event

 

Yes. But in my experience they've broken me off the approach, not the guy behind me.. and seems to be a common trend here that the dude in the 172/PA28 at 85 knots gets vectored off the approach for "faster traffic behind you" - we asked about this at one of our club events that had a few local controllers do a Q&A. Their response is not that they play favorites to jets or "the big boys" - but that vectoring around an 85 knot light airplane is much easier than vectoring around a 160 knot jet. That jet covers twice the ground and takes twice as wide of a space to turn as the other guy does

 

Fly any speed you want until a stable approach speed is needed at the FAF in order to time the approach...

We still fly timed approaches, don't we?

 

I think the right end of the answer would be that every professional pilot should be configured, and on-speed or at Vref by FAF. Or at least correcting to it. If it takes you a few miles prior to configure and get there, nothing wrong with that. If you feel like you are "dragging it in" at your own personal comfort level, then bump it in closer a mile at a time and see how it works out. Not advocating being a jerk, but nobody behind you in the conga line really owes you anything. Obviously certain airfields will prioritize revenue traffic if you become too much of a hassle, but I wouldn't worry about someone else's plan over your own goal of arriving at FAF with a stable approach.

 

At some point you need to be "stable" on the approach. Many, if not most, CFII teach the FAF as that point. As you've learned that makes life easier especially for the new instrument pilot. But does it need to be a geographic location. Airlines for example know that they need to create a specific rule and tell their crews to adhere to that rule. At the same time you may be shooting the ILS into ORD on one leg and the DME Arc circle to land into KIMT - Iron Mountain MI - on another. So our rule was as I recall (and note I haven't flow 121 in about 25 years) stable by 500' above DA or MDA. The next question was what does stable mean? It means in the landing configuration, needle(s) within limits (1 dot), speed Vref -0/+10, VSI less than 1000'/min. Now you are in a position to make a normal landing out of the approach.

Note, you can adjust these for your own comfort level.

Example in real life. A Shorts 360 is the box other airplanes come in. Speed? Ha. But ORD wants 180 to the marker. Level the best we could do would be about 150 heavy, a bit faster when light. The technique I and most others used went like this. Upon intercepting the slope, usually several miles outside the marker, fly 1 dot low. Aircraft could easily give me 180 down hill. Nearing the marker flight idle, pitch up to maintain the slope or go a dot high if heavy. At 150 start hanging things out. Stable at 500 above DA. Notice how flexible yet safe the rule was. No need to worry about the criteria prior to the marker. After the marker you have 1000' of altitude about 2 min. to slow to Vref + 10.

This works well in a Mooney M20J. Twr: "What is your best forward speed?" 20J: "140 level 170 downhill." Now they know they can turn me in further out and I'll be keeping up with the jets (almost). The only difference was on the Shorts HSI one dot was half scale. On the Mooney HSI I fly half scale. The only really big difference between Shorts approaches was noise. In the Short we could silence the gear horn when we wen to flight idle with the gear up. In the Mooney you cannot. I just need to put up with it until I lose the speed and put the gear down. CAUTION especially nowadays some approaches will take you below a published min. altitude if you fly the slope outside the marker or FAF. KNOW YOUR APPROACH!

In the ATR we could use this technique to maintain 250 to the marker if asked.

So to recap establish a stabilized approach criteria. Be strict about it. IF YOU ARE NOT STABLE GO MISSED! Fly a technique which will give you a smooth transition to meeting your stabilized approach criteria. The technique is established by thought first then followed by trial, error and finally practice. Good luck.

Edit - stylistic correction.

 

It depends on what I am flying. My goal is to be at my chosen approach speed by the time I hit the FAF. In a "dirty" 110-120 kt cruise Piper or Cessna, that might be as little as a mile or two before. In a 180 kt cruise Ovation, it's not a one-time act for me and the process starts much, much, much earlier.

 

Depends a bit on the approach for me. For vectors, I'll slow to 90 kt when given the final vector to intercept the final approach course. If flying by own nav, I'll slow to 90 kt prior to the FAF. However, if flying a procedure with a HILPT or other course reversal, I'll slow to 90 kt to fly the course reversal. Basically, slowing to 90 kt puts everything in a known power and attitude configuration for procedure maneuvering for me. I can do it faster if absolutely required, but it's not my first choice, especially for a new procedure.

 

There is no one size fits all answer. Depends a ton on the airplane and the situation. Some planes can maintain cruise airspeed to the FAF and then quickly decelerate. Others, you have to start slowing 30 minutes out.

How I fly an approach in the Beech 18 is very very different from how I fly them in a Baron. And how I fly an approach into BOS/PHX/CLT is very different from how I do it at my home field.

 

My first reaction to your post is "Why is he concerned about the other pilots? He should carry out his duties as PIC and let other pilots deal with their own problems."

If you want a stabilized approach for the entire final approach leg, be at approach speed as you near the FAF. So it feels like you are dragging it in..so what? Unless a tower asks you to keep your speed up, final approach speed is your decision based on what the POH calls for and the weather dynamics on a given day.

 

Call me slowpoke, I guess. I usually slow to approach speed just prior to the IAF. I fly the entire approach at 90 kts, which is about 17"MP, and 10°flaps in my Arrow. Usually about 1 to 2 miles from the IAF, I'll dial it back and let the speed bleed off enough to get that notch of flaps in, and then get trimmed up for 90 kts. I like to be slowed down and trimmed prior to hitting the IAF. That's one less thing to worry about as I am flying the approach.

I'm curious, but to all those that are slowing just prior to the FAF, are you carrying cruise speed in the approach prior to that, or is there some intermediate speed used? Do you fly procedure turns at cruise speed?

I've never been asked to keep my speed up while flying an approach. I have been asked when VFR, and I've happily obliged. I'm pretty sure I wouldn't crank up to cruise speed while flying an approach.

 

Yup, last week I was told to "slow to and maintain under 160 knots please" by Boston approach, lol. Usually it's maintain best possible forward speed. It just depends.

 

I've been spoiled by being able to select the speeds at the FAF and MAP/DA and letting the system slow me down without doing any of that old fashioned "flying" stuff...

 

AIM aint what it used to be. Last year, it said, for airplanes, the stabilized speed between the FAF & MAP determines your approach catagory. It was in AIM CH5, Sec. 4. Can't find it in this year's version. More years ago, that reference said you had to fly the entire procedure at a stabilized speed. How about procedure turn out bound at 90KTS if you want Cat A ?
You probably don't give a hoot about helos, but they have it different. AIM 10-1-2 says they can fly the whole procedure at the highest speed of the highest catagory. Thats E, 266KTS. Just as long they cross the MAP at no more than 90KTS. (Then FAR 97.3 applies and you can cut vis minimums in half.) They make autopilots that handle the decel for you.
.

 

Cruise is 150-155kts, a little more in the descent. At the FAF (if there is one) is where I want to be at gear extension speed. (150mph) Fuel pump on, gear dropped, slow gradually to flap speed to hit that at the next fix (if there is one). Barring a FAF or fix beyond it, 5 miles for gear extension, 2 miles for first notch of flaps. If its mins, 2nd notch of flaps prior to breaking out. Full flaps once runway is in sight.

 

It depends largely on the aircraft. A Warrior or 172, your cruise speed isn't that different from your approach speed, and it takes about 5 seconds to get there.

Something faster and slicker with retractable gear, you have to plan your descent and approach speeds a little better. The Comanche cruises at 160 kts, but I usually fly 90-100 kts on the approach, and need to get to 130 kts (150mph) to get the gear down. It is not an airplane that likes to go down and slow down at the same time, so you have to be ahead of it.

 

Correct. In King Airs I could keep 250K until 5nm. At busier airports ATC has requested 160K to the FAP/FAF a lot. I am now based at KADS/Addison, TX and we are usually asked to slow because of all the single piston training aircraft.

 

I love requests like these!

These days I fly the whole thing as fast as I safely can and within ATC compliance

 

If the air is smooth I just leave everything alone and follow the altitude assignments, etc. as needed. In the plane I fly the yellow arc doesn't start until 178 knots indicated.. if I'm flying legal speeds and ATC doesn't have any issues with spacing and the approach is stable and controlled then I don't see the value in slowing way down, nor do I see any issues in keeping in the speed

Flying is fun, but it's also a utility to get somewhere faster than a car. I guess I just don't see a benefit to slowing down that much way out. I'm usually 120-130 at the FAF and will gradually slow down from there.. get some flaps in, and not get under 90 knots until short final

That's also plane dependent, 90 knots is basically the minimum speed you ever want in a Cirrus unless landing is imminent

 

..there is no rule prohibiting or advising against flying procedure turns at "cruise" speed. The requirement is to be under 200 indicated. I'm not sure there is any common SE GA piston plane that can manage over 200 KIAS cruise

Granted, if you approach the final approach course at 180 knots and ATC gives you the last turn vector for the final the autopilot will likely blow through it or you'll end up turning much steeper than standard rate.. so planning and stability is required at all time

But generally speaking, if it can be safely done so I don't see anything wrong with keeping the power in and letting the plane pickup some downhill speed

 

Again, depends on the airplane. Fly at 180 kts in a Mooney to near the FAF, just ain't gonna slow down to my 105 approach speed (even with speed brakes). In that airplane (and a few others) I have an intermediate speed.

 

Cirrus has standardized how to fly approaches. For the piston aircraft they say 120 knots before the IAF, 120 until 2nm before FAF non precision or 1/2 scale below the GS for precision, at those points you put in 50% flaps and be at 100 knots by the FAF or GS intercept. Maintain 100 knots during the descent. Below 500 feet they want you to maintain 50% flaps for landing. Above 500 feet agl you can go full flaps if you have the field in sight. Field in sight you slow to final approach speed, other wise stay at 100 until you go missed.

Works pretty well.

 

You need to be able to be flexible. Years ago, flying into CHS, a joint civilian/AFB, in a 172, I was told to slow down for a flight of two F106's to land before me, then moments later "maximum speed for a flight of four C141's". Flying into busier airports you should be capable of responding to speed requests outside your normal.

 

"Acme Air, maintain 250 to the outer marker, 200 to the middle marker, we'll call your flare."

 

Part of being flexible is knowing when to say “unable”

 

It is like teaching. It has to be appropriate to the audience and you need to have a few repertoirs in your bag, even as you have a favorite regimen.

Seneca N3__55, maintain 8,000, heading 090, intercept the localizer, descend per the glideslope ILS 4R, maintain 170 kts. You're number eight for the field.
(Yipes!)
Chicago approach 32755, 8,000 and 090 to intercept. 170 knots. Please pass along to tower that the last mile will be very very slow. NOT yet cleared, will continue".

If you wanna join the conga line, you gotta fly the conga line.

 

250 to the marker.

 

This, I was taught to tell them what you are comfortable with when they ask or tell you what to maintain. For me, it's 150 until 2 miles before the FAF, then 100 until short final.

 

We talk a lot about "keep your speed up." My personal favorite was the opposite. I was flying the ILS 7 into KORL and asked to slow 10 knots.




Punchline: I was in a 172

 

So they basically asked you to stop

 

...and hope there is not a head wind.... The heading of this 172 is actually 006. We were flying backward at 17.2 kts.