Attitude for airspeed and power for rate of descent on approach is the methodology of choice for most flight training organisations involved in elementary pilot training – but is it correct? The short answer is yes and the long answer… well, kind of remains yes – but that doesn’t mean that there’s possibly a better way of flying the approach. There’s a small fraternity of pilots that insist upon teaching attitude for profile and power for airspeed, so this short blog is about addressing my experience with the two methods. Keep in mind that I remain open to both methods and am still yet to favor one over the other in early training. This blog details technique flown during an approach to land with a comparison between light aircraft and jet types.
When you’re undertaking your elementary flight training, you’re likely to be taught “attitude for airspeed and power for ROD”; then when you start your instrument rating, you’re likely going to fly “power for airspeed, attitude for ROD (or flight path)”; then if do an instructor rating, you’re going to be taught a combination of the above and also introduced to “Point & Power”(gun-barrel or ballistic!) approach and the “point of no relative movement” approach. At the end of the day, they’re all a function of “Power + Attitude = Performance” and both methods essentially accomplish the same task. They’re both taught for their own good reasons.
One pilot I knew used to use the following to explain his preference and disdain for attitude for airspeed:
“Next time you line up for takeoff, and since attitude controls airspeed, lower the nose until the aircraft accelerates to takeoff speed. When flying speed is reached and you want to climb (and since a climb is a negative descent), open the throttle to achieve the desired rate of descent”.
An old adage in aviation reads as follows:
“When you push down, you go down. When you pull up, you go up. If you keep on pulling up – you will start going down again!”
There’s not a pilot alive who hasn’t heard this saying, yet most of us ignore the basic principle in the approach phase of flight. There is reason for it…
In elementary training, instructors generally keep to attitude for airspeed and power for rate of descent for a few reasons, none more important than the fact it seems to work. The technique is historically rooted in approaches that were taught in very low powered aircraft such as a Tigermoth that often used idle thrust for the approach. Attitude became the primary method of controlling airspeed, with a combination of s-turns and slips used to control the rate of descent. Aviation training is quite resistant to change and the attitude for airspeed technique has propagated its way around training circles and remains the technique of choice – even if it isn’t the most appropriate method (and I still don’t know which I prefer!)
The attitude for airspeed approach might be considered an easy technique to apply. It offers the student continuity in methodology. From the first lesson you’re shown and told that pointing the nose up reduces airspeed. You’re taught that in a climb your airspeed will reduce. You’re taught that lowering the nose will increase airspeed — and it’s a practical application that repeats itself through most phases of early flight. It’s a simple submission that tends to sit well with most students because they can see it work – and it does work… but we are applying the secondary effects of controls to fly a vertical profile. If you’re flying a small training aircraft and apply thrust the aircraft often tends to pitch its nose up with a secondary reduction in airspeed, while reducing thrust usually has the opposite effect – an effect not likely felt in larger aircraft due mainly to the coupling of the center of gravity and center of pressure in the design phase of training machines. Light aircraft also have slipstream over the tail… an aerodynamic effect not felt in jets. Even when a pilot uses power to control airspeed in a light aircraft he will inevitably have to make an attitude adjustment anyhow – so why not use this coupling effect to our advantage?
Lower inertia light aircraft are often underpowered and flown very close to the tail end of the drag curve during an approach. If you’re airspeed reduces on final (due induced drag), additional thrust in isolation may be insufficient to increase airspeed. Lowering the nose has an immediate and noticeable effect. If you’re going to teach somebody to lower the nose on final for airspeed, you want to make sure there’s power there at the same time (to arrest the rate of inevitable descent). The other method tends to ignore the potential for an approach on the back of the drag curve with insufficient power to overcome decay of speed and the likely high rate of descent. The ‘attitude for airspeed’ approach is almost like a safeguard for low time pilots who don’t have sufficient knowledge to properly pick and choose and then apply a broader range of techniques most fitting to the approach. Attitude for airspeed is a simple proposition that works on the approach in isolation of any other. Keep in mind that we have to teach a method that is ‘safest’ in the early stages of solo flight in the circuit. If you’re low and slow in a training aircraft and pitch the nose up to maintain profile, what comes next? Teaching power as a primary method to maintain profile might be considered an insurance policy against inexperience or a stall. Pilots will adopt more technically correct methods later on when their proficiency and skill permit it.
In larger types, a small change in attitude translates to a huge shift in VNAV performance. In some aircraft just raising the nose by one or two degrees will give you an immediate and substantial rate of climb (or descent) whereas it’s unlikely to have the same effect in lighter types (Rule of thumb: 1 degree of pitch change equals a change in vertical speed of approximately 2% of the airspeed). In a jet, applying a small amount of power has a noticeable effect on airspeed. The same can’t be said for piston touring aircraft.
From an instrument flying perspective, power for airspeed and attitude for rate of descent is virtually the only method that applies (and logically) works on an ILS, RNAV, VNAV or similar approach since we’re flying a strict vertical path. It’s normal to set an approach power setting and then fly the glidepath by adjusting your rate-of-descent with attitude alone, and airspeed is unlikely to substantially affected. Should you need to target a particular airspeed you will achieve this with the use of power. Adjusting power every time you are high or low is quite an absurd proposition, and subtle changes in attitude alone makes it far easier to fly a stable approach. In any aircraft with a flight director it will command changes in pitch and not airspeed. The ILS course-bar (localizer) and glideslope essentially do the same thing.
In most twins, and particularly turbine or jet aircraft, trying to fly a visual circuit with the use of power is virtually impossible. You must pitch the nose up or down to effect a rate of change to maintain your visual approach profile and you must use power as appropriate to maintain airspeed. In a light aircraft, however, we have a very narrow range of speeds, and a slow cruising speed, and low inertia, so power is actually quite effective.
What method is easier? In my experience I’ve found that teaching somebody to fly an approach using attitude for airspeed isn’t quite as effective as simply teaching them to fly a vertical profile with attitude. Teaching attitude for airspeed requires a relatively complex set of cause-and-effect instructions to trigger requiring coordinated control inputs to maintain the new profile. Using attitude for flight path is more sympathetic to students flying high or low on the approach, meaning that if they’re high or low they can simply adjust their attitude so their aiming point remains in a constant position in the windscreen. Power is then simply used to maintain the approach speed. Most trainee pilots drive a car so the simple proposition that power increases your airspeed is easily applied.
I believe that anybody wanting a career in aviation – particularly in jets – should apply the ‘power for airspeed’ principle simply because it’s used in commercial jet types. There’s no use learning one method only to invariably adopt another method later on – particularly since it is the only method that truly (and practically) applies in commercial aircraft. Most flying schools training cadets and airline pilots are most likely going to insist on the technique that will remain consistent throughout all their flying. Having said that, in most singles and even some lower powered twins, attitude becomes a valuable means to the pilot in maintaining a profile when power alone is insufficient to accomplish a change in airspeed – particularly in the world of light aircraft where the approach is flown very close to a region of the drag curve that constantly conspires against a stable approach speed.
Flying schools will generally adopt a method and training technique that is most appropriate to the student. Even when I was forced to teach one method by a flying school’s training manual, I often reverted back to another method when necessary to give the student another point of view. Seeing the same approach flown from another perspective was often enough to give the student a better appreciation of the approach and made it easier for them to adopt another particular technique.
There are some organisations – particularly some military schools – that teach a combination of the above; Power for rate of descent around base but then reverting to attitude for aiming point on final. Personally, I don’t see any sense in intentionally mixing the two techniques during the ab-initio stages of flight training for the sake of consistency. Whatever method you use from the beginning should apply throughout your entire approach.
Every method has it good and bad points. Pilot training should be personalised so that the most appropriate technique is taught from day one. Regardless of what method is used, one universal truth prevails: Power + Attitude = Performance.
Version 0.1. Under revision.
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Ah the old argument.
Real aviators landed airplanes on ships by flying alpha and varying power to control the sink rate.
Pilots of the blue persuasion insisted on landing on long runways by using power to control airspeed and attitude to control the sink rate.
I like the navy way!
But in the middle of a dogfight, I doubt they would use attitude for speed and power for climb/descent. Why the switcheroo on final approach? Explain why the Navy does it this way instead of the other way. I’m curious.
Yes, Pete, but I’ll bet you don’t do it that way in your 777.
Best discussion on the airspeed and attitude debate that I’ve ever read. Printed for the flying school magazine. I hope you don’t mind?
The RAAF teaches power for speed, and attitude for glidepath. It’s easy to understand, works, and it’s accurate. And it then translates to every other aircraft type that they use, so you don’t have to learn another method.
The navy actually flies(flew) both an an AoA approach, and an airspeed controlled by power approach. Flying alpha in something like an A4 was difficult to learn and hard to do accurately, but it allowed you to fly way down on the back of the drag curve….well below where any sensible person would want to be flying. It allowed you to arrive on the ship with the minimum energy…an absolute necessity. On shore bases it’s used for practice, but if you want to make air force style smooth landings, then you needed to be a bit faster, and so use the other method.
John,
That finally explains it! Even my father, who landed A6′s on carriers, couldn’t explain it that clearly. (To his credit, I probably didn’t pose the question clearly either.) The beauty of AoA is that it automatically takes all the conditions into account and gives you the slowest possible speed upon arrival.
All of that being said, I am a firm believer that attitude flying is THE best way to teach pilots in the general aviation world. The problem is that there isn’t a consistent method of teaching it. The FAA gives us the old ATTITUDE + POWER = PERFORMANCE line and then instructors are supposed to somehow translate this to something a student pilot can see and understand.
Anyone who is seriously interested in teaching the attitude flying technique with a method that works should speak with Jim Brannan at Mazzei Flying Service in Fresno, CA. (www.flymfs.com) It all starts with placing a small mark on the windscreen with a grease pen. This mark is the attitude reference–and it is what separates those instructors who just spout the FAA line and those who actually want their students to SEE it. You have to SEE it, not just imagine it.
Hi Andy. Really interesting comments. When I was teaching I carried a pen in the cockpit so I could make a mark when necessary. A small bug was often enough to illustrate the point.
John’s comment is fantastic. JB was the Captain of QF30 (the Qantas 747 that had an oxygen tank go walkabout in 2008) and we recorded a 75 minute interview with him a short time ago that we’ll be releasing this week.
The term “bug” reminds me of my first instructor (a genuinely good guy). At one point I remember him mentioning to “pick a bug on the windscreen” and use that for some maneuver. I was totally lost. Eventually I figured out he meant to literally pick a bug–a dead bug on the windscreen–to point the airplane. Problem was that there were dozens of dead bugs on the windscreen and it’s useless unless a prominent bug smashes the windscreen right in the position that represents the attitude of the airplane from your point of view. Other than that one instance, I was trained as a power for glidepath and elevator for speed guy. When I did my commercial training, I found out about the “good news” of attitude flying. I’ve been “reformed” ever since!
And here’s another method for you…also from the A4G.
Put 170 mills on the gunsight (just a setting, don’t worry about it). Hold the cross hairs (pipper) on the end of the runway, and don’t let it move. Control speed by varyiing the drag (gear, flaps, speedbrakes). Approach IAS…around 200-220 kts. Start flare at 400 feet AGL.
I also want to comment on something from the original blog post.
I don’t believe that either method is the same outgrowth of ATTITUDE + POWER = PERFORMANCE. Here’s why:
Pilots who use power for glidepath control typically don’t give a darn about their attitude. The idea is to trim the airplane for a certain airspeed and then don’t touch the elevator. Once the magical trim setting is achieved, just adjust power to maintain the proper glidepath. In my mind, the formula for this way of flying is ELEVATOR TRIM + POWER = PERFORMANCE. A pilot who flies like this doesn’t care if the nose is pitched down 3 degrees or 5 degrees or 1 degree. All that matters is that the airspeed is on target and that the airplane is maintaining its glidepath. Nowhere in this approach methodology does attitude come into the picture.
I think there is a place for this type of approach, but it’s not during the first 10 hours of flight training. If you were flying an instrument approach without an attitude indicator, then this method is the basically what you’re stuck with. Or, if your engine quits and now you have a glider, then you are stuck with using the elevator to control airspeed. These are band-aids to solve specific problems that may arise in flight, but why would we try to fly like this when everything is normal?
Consider this conundrum that a keen student who is taught that power controls glidepath might notice. (This is to reinforce what was stated in the original post.) We’re on approach and we’re on airspeed, but we’re starting to rise above glidepath. I instruct the student to reduce power to return to the glidepath. Everyone knows this works. But what actually happens when the power is reduced? Doesn’t the nose drop and assume a steeper nose down pitch attitude all by itself when the power is reduced and no other changes are made? So what is actually causing the airplane to assume a steeper glidepath? Is it the power reduction or the new attitude the airplane is flying at? In the end, it’s the fact that the attitude has changed that causes the airplane to change it’s glidepath. We changed the power–but that changed the attitude–and that is what caused the change in glidepath.
And we can talk about how this change is different in different types of airplanes depending on engine location, control surface location, etc.–but the difference is in how fast the attitude will assume a new position, not a matter of if it will happen. A 737 will pitch down if you reduce power and wait–it will just take a longer time to happen. In a Cessna 172, the change is immediate.
Also, I don’t believe that small airplanes need to fly any farther up on the drag curve (ie slower airspeed) on a normal approach. Approach speed is typically 1.3 x stall speed, and I might be wrong, but this is pretty consistent across all airplanes. Again–there are exceptions–such as landing on an aircraft carrier or landing on a sand bar in the middle of a river, but these are exceptions and certainly not what we want to be teaching pre-solo student pilots.
Finally, I want to ask a question to all the instructors out there who still teach students to control their airspeed with elevator and trim and control glidepath with power. When you are flying by yourself and not teaching, do you actually fly like that? Pay close attention to your own flying technique the next time you are pleasure flying or out on a charter… are you really flying the same way you teach your students?
Best regards to all–especially to all the instructors out there squeaking out a living on little pay, but keeping the interests of their students first!