Fred Scott, Jr.
(434) 295-4188

Angle of Attack
From our Navy and Marine Aviators. They know...
... and EVERY ONE of them owns a light aircraft

(Click here to go back to the start of our AoA pages)

We are NOT ( !!! ) SUGGESTING that light aircraft pilots suddenly attempt to become Naval or Marine Corps Aviators so as to land a heavy jet on a pitching deck at sea [Let's get over this idea, right now. But for those who can't ... here's your Walter Mitty image for today. Note the "On-Speed" AoA on the glareshield and the "centered meatball" on the far left. This looks... PERFECT!] ...

...or bush pilots who need to squeeze out every ounce of performance, almost always at Gross Weight, too.

For me, a reliable early warning of impending stall (listen to Slow Sarah's "Getting Slow!") is a plenty good deal for ~$550- $1,500 plus a few hours of installation.

Consider these thoughts from Brian Cantrell, a highly trained Naval Aviator (he snapped "Coming Aboard" from his E-2C Hawkeye), currently employed as an airline pilot. A Beech Bonanza owner, Brian writes:
"I like it that AoA indicators are starting to gain some popularity. I was a Navy pilot. We used AoA almost from Day One of flight training. The T-34Cs that we flew in primary [similar aircraft to our Bonanzas] were equipped with AoA indicators.. After the initial "FAM[iliarization]" stage of training, we had a short aerobatic stage where we learned to use AoA in maneuvers and for precise speed control to precision landings. As we moved on to jets and began learning how to fly carrier approaches, we used AoA all the time.

"Obviously, we don't land Bonanzas and Barons on a carrier -- but as C.K. Lee mentioned -- an AoA indicator can be very useful in all phases of flight. C. K. also mentioned that 'most folks know the straight-and-level stall speed of their plane'. I'd wager a little differently:

"They probably know the ballpark speed, but THAT SPEED CHANGES BASED ON GROSS WEIGHT. The range of stall speeds for a light Bonanza might be 5-7 kts slower than for a fully loaded one (that's just a ballpark guess). In the Airbus A300 I fly at work, a very lightweight approach might be flown at 120 kts, whereas a heavy approach will be flown over 140 kts - and both have the same stall margin."

Building on their...."all phases". Right On! Consider the TIGHT TURNS. Jack Stovall flew a fake landing pattern at altitude (in an unfamiliar cockpit, to boot). On Downwind 'on the donut' (~95KIAS), he turned base, then to final while descending at ~500 FPM. Bank angle never exceeded 30 degrees. Total offset distance between downwind track and final? About 200 yards, maybe less. All done under FULL CONTROL and with a KNOWN SAFETY MARGIN. That’s a very tight turn in a King Air, a very useful arrow to have in one’s quiver sometimes.

Slow the aircraft to just above stall and the turn radius goes WAAAAAY down. Every bush pilot knows that. Brian observes, importantly, that speed/angle will vary greatly with cabin/fuel and G loading. In a steep bank, the ASI is the AoA gives real comfort that the maneuver is within a safe margin. In VERY TIGHT TURNS, an AoA helps ... a LOT!

Here's CDR Dan “Lobo” Turner; an F/A-18 Pilot and Beech Bonanza owner:
"My personal Bonanza has an AoA indicator; I like it very much and it helps me a great deal. It is called a "lift indicator" [it was designed by the same Mark Korin, incidentally] and has its stall AoA at the 3 o'clock position.

The huge safety benefit for us Bonanza pilots is the confidence it gives us at heavy weights both for efficient rotation and flight out of ground effect on takeoff, and for the landing pattern. I religiously fly the "approach speed" value instead of a rough airspeed.

"I also have a few hundred hours in the T-34C and I loved that AoA system too. "

Jay Apt, NASA Astronaut. Beech Bonanza and Twin Beech owner:
“An AoA is one of the great safety enhancing devices that have come to aviation. You might consider one if (a) your gross weight changes significantly (i.e. you change the number of pounds in the cabin or take long flights where you deplete a significant fuel load), and (b) you want or need to land at the proper speed for your weight. We flew with them in Uncle Sam's aircraft, and they were great. This system (the "Legacy") seems very similar in presentation and capability to what we flew in the T-38. My own view is that in aircraft with large changes in weight (in the T-38 due to fuel, in our airplanes due to both fuel and payload), an AoA is a really fine safety system. For roughly the same price as a Garmin 496, it is a very good thing to have. I've looked over the flight test report, and (while it is not fireside reading for many folks), it seems to me they have done their homework.”

John "Eddie" Paysse. An F/A-18 Simulator Instructor, Navy “Top Gun School” graduate, and Beech 1980 A36TC Bonanza owner:

"I have almost 1,000 hours in the military Beech T-34C with the AoA gauge. Most of my use of the T-34C for us was acting as an airborne observer/safety officer for the F-18s dropping bombs. We'd be at 500AGL (or less!) doing racetrack patterns to get into position to clear guys hot to drop or shoot the gun. To do this, I'd hawk-eye the AoA gauge for every turn! 20 units was our L/D max and used for 'on-speed' when flying AoA landings. Max lift was, I think, 27 units, buffet happening at 28.5 and full stall at 29. I would always target no slower than the 20 units in those hard turns down low or when wrapped up in the approach turn when landing after coming into the 280 KIAS (Vne) overhead 'break'.

The Navy gauge was installed so that 20 units was at the 3 o'clock position so it was easy to target that AoA with a quick glance when loading up the plane in those cases

Needle high? Push it down.
Needle low? Pull it up.
(except when inverted, of course)

"You can see that my Bonanza AoA is set up the way (i.e., level needle at 3 o'clock) as is Dan Turner's. I have 15gal tips tanks and my current flights have me ping-ponging back and forth to both ends of the weight-loading envelope all the time. For me, the $500 I spent on the system was a no-brainer. With a good understanding of what AoA will give you and a little practice of incorporating it into your normal scan pattern, I think anyone can fly a better, more efficient and SAFER Bonanza!!"

Here's an article on the installion of the nearly-identical LRI; there are really good pictures of the installation details. The same engineer designed both the LRI and the AlphaSystem mechanical display. As far as I can tell, they are substantially identical, but AlphaSystems has a much wider product line and has made more progress with the electronic displays.

Brian “Nemo” Niemi, Naval Aviator, American Airlines Captain, Beech Bonanza owner (with its AoA being installed soon): "You are about to test fly an AoA product? I for one say “Full Steam Ahead!” My training in the Navy showed us students the incredible amount of information extracted by a easy-to-read AoA gauge.

I fly for American Airlines. Most of AoA information is hidden from our PFD glass displays. The only instance when AoA is displayed is during wind shear alert. A PLI line is displayed to extract max performance for the 'escape maneuver.' Our chief pilot has mentioned that AoA information will be moved to our primary flight display sometime soon. I believe they see the benefits of having this front and center."

Note, added April 2011: They did it! This American jet is flying at 2.2 Alpha inbound to O'Hare. See the top right portion of both the PFD and the HUD. Here's a superb discussion by Boeing.

"I was wondering if the major flight universities have yet taken a serious look at any AoA product. If I were in charge of instructing new aviators, AoA would be installed in the training fleet. Period."

UPDATE, as of June 2015: the student-training fleets at Liberty Universiy and at Embry Riddle Aeronautical University have been equipped with AoA displays. That's just wonderful news.

Bryan "Betsy" Ross is a Naval Aviator too; he flies a Beech 58 Baron:
"I learned to fly AoA, and flew it exclusively for 10 years in the Navy before transitioning to General Aviation. I was always amazed that AoA wasn't the norm. I'm glad to see it becoming more mainstream. AoA really is the only way to go.

"I am an active Reservist, still instructing young Naval Aviators in the T-45C Goshawk. I fly for Delta in my other life, and have the Baron for family use.

"I grew up on AoA, as all Tailhookers did, and am a big fan.  In fact, I wish the airliners at Delta had a Navy style AoA on board.  AoA is, simply... an easier, safer, and more effective way to fly"

Matt "Stink-Eye" Stettner is an active duty Navy Advanced Flight Instructor. He has never flown a Legacy AoA in a light aircraft -- so he's a bit more cautious -- but he is currently installing a Legacy in his P35 Bonanza. "I would be VERY interested in installing and publicly reviewing an AoA indicator for my P35.  I have ~2,000 hours (and climbing) of Navy tailhook time.  I'll admit, I am skeptical of the utility when not trying to land at the boat or when dog-fighting another aircraft, but I am very interested in trying it and learning to use it in my civilian airplane."  NOTE: Matt's caution is well-advised, but your host hereby predicts that we he returns fom deploiyment, we'll hear more from Matt on a slightly different note!

Jim Cear, military C-130 pilot and Bonanza V35B owner.

"I spent 40 minutes on the phone listening to Mark Korin of Alpha Systems/AoA. What a pleasure to find someone as passionate as he is and so intent on saving GA lives. Having flown with AoA in the military, I'm embarassed to say I never knew it was available for GA aircraft. For ~1,000 bucks, I don't understand why it isn't in every single engine trainer, especially when they spend 20 or 30 times that on glass panels. I just placed my order with Alpha Systems....very cool product."

Douglas Trainor, retired FedEx Captain. Former Marine aviator. Beech Bonanza owner:
"It's a wonderful idea to make AoA an easy and affordable addition to light aircraft ...You have garnered a lot of attention and 'proof of the pudding' materials that stand on their own -- more so than any current info of which I am aware. No comments I have heard indicate either a lack of interest or a lack of appreciation of AoA."

Al "Easy" Aitken retired from American Airlines after a Marine Corps career that included being a test pilot for the USMC F/A-18 Hornet and the Senior Fixed Wing Test Pilot Instructor at the Patuxent River Test Pilot School. He's a Beech Bonanza owner and he wrote this AoA test flight plan, helped fly the plan, and helped write the Final Reports on the Bonanza's AoA and King Air 90's AoA
"An AoA system can provide the pilot valuable information and can help us fly more precise approaches at “correct” airspeeds. It will, of course, provide us with that correct information whether wings level or approaching accelerated stall. AoA information was critical in our swept wing, exceedingly less forgiving, military jets. It was especially useful in allowing us to fly our approaches to the ship as necessarily slow as possible for obvious reasons.

"One thing I particularly like about the AlphaSystem Legacy AoA -- which I am installing in my Bonanza -- is that it presents trend information; as we get closer to stall, it becomes more active in alerting us. A stall warning vane/horn provides some protection from critical AoA/CL, but only about 7-10 KIAS above stall AoA, and provides no continuously progressive information from its onset to the actual stall. On the other hand, an AoA indicating system provides earlier indication of approaching trouble and a continuous display of narrowing stall margin…regardless of airspeed, attitude or flight conditions. Airspeed will lie to you, AoA will not.

"Ultimately, no matter which manufacturer's product a pilot selects, I believe that... affordable, simple AoA system installed in general aviation aircraft for pilots well trained in its use and application can enhance aviation safety"

"AoA is the future. It will become standard on all airplanes as the understanding of and enthusiasm for it grows among our general aviation pilots."

Steve Nicholson flew the A-6 Intruder in the Marine Corps and heavy jet transports for Northwest Airlines. He's a good friend and nearby neighbor here in Virginia. Steve's observations--submitted here after flying with me in my AoA-equipped King Air--on the various ways of using an AoA are particularly interesting:

"As AoA displays are added to the general aviation fleet, it may be important to discuss the differences between the "Pitch and Power" method taught in Naval Aviation and alternative techniques that are taught in commercial and general aviation. There do seem to be some differences of opinion as to how the AoA indicator should be used.

"For example, you probably already know that during an approach to the carrier, glide slope is flown with power; airspeed (AoA) is flown with pitch. The red chevron (which conveniently points down) on the Legacy tells a naval aviator that he is "Slow" (high AoA) and needs to lower his nose to achieve “On Speed” (the green donut). Lowering the nose would cause the aircraft to fly below the glide slope - a situation that calls for the addition of power. So the proper correction for the naval aviator in this instance would be to ease the nose down (probably with a tiny bit of nose-down trim) while he adds a tiny bit of power. These corrections become automatic, as you well know.

"In contrast to my naval aviation experience, at Northwest Airlines I was taught to fly glide slope with pitch and airspeed with power. A "Slow" indication on the Legacy would call for a power addition to correct the "Slow" (high AoA) and a pitch correction to maintain glide slope.

"My point is that the aviator’s background and experience will determine which method he implements to correct from an unsafe AoA situation.

"Both are correct procedures when considered on their own. But bad things could happen if the instructors co-mingle the two equally-good techniques.

"You have a great instrument giving you some very timely information. How you correct from “Slow” (high AoA) to “On speed” must be determined by the specific pitch and power method you are employing.
"The Legacy display looks fantastic. I like the glare shield location (not too far off to the side) as the best position. The idea is definitely to see the indicator in our peripheral vision– that's the whole idea behind the red, green and yellow color changes.

"During a carrier approach, we have no time to come "eyes inside" to the instrument panel to check AoA. In fact, we don’t have time even to directly scan the AoA indicator – we must recognize the hue of red, green or yellow and make the correction. I am glad there is an integral dimmer for night operations. We want to sense the hue of colors – not get blasted in the eyes with them.

"I noticed you have an indicator on both sides of your cockpit. That is great. Traffic patterns flow both right and left.

"We had a circular type AoA gauge on the instrument panel that was great for night and IFR operations. We would use it on the approach, then transition to the Legacy-like indexer on the glareshield, when we broke out. We don’t want the pilot to have to raise his head to view the indexer when he is on a nasty approach and fighting vertigo. so if there is to be only one AoA display, make sure it is located in the eye's periphery.

"I have a personal story directly related to AoA bailing me out (probably saving my life) of an airspeed failure in an A6 Intruder during a cat shot on a real dark night. As I came off the catapult, my airspeed was falling rapidly but my AoA indicated "fast". I had to choose one instrument over the other. If I was wrong, I was either going to pull into a stall or fly myself and my BN into the water. Either incorrect action would have killed us both. I went with AoA. I pulled to the pre-briefed AoA attitude (22 units if I remember correctly) on the round AoA gauge on my instrument panel. My BN was yelling “airspeed, airspeed, airspeed!” through the hot mike as he watched the airspeed deteriorate. I transmitted to him to monitor AoA and VSI. With AoA pegged at optimum and a steady rate of climb, we knew almost immediately (it seemed like forever) that we had made the right choice. I flew AoA the entire flight and made a routine trap later that night. The problem was a pitot-static system failure related to my airspeed indicator. At an altitude of 60 feet off the bow of the ship in the pitch-black night, had I lowered my nose to correct for the erroneous slow airspeed, I would be dead, I’m sure.

"MY POINT IS: BRINGING AoA INTO YOUR SCAN CAN AND WILL SAVE YOUR LIFE! I know we have to teach airspeed as primary...but I can tell you from experience, if that is all you’re looking at, trouble may find you.

"Overall, I think the Legacy display and these flight tests are fantastic. If I owned a plane, I would, without question, install one and USE it!"

John "Tramp" McMurray flew the F-4, F-15, F-5 and AT-38 in the Air Force from 1973 to 1998.  He now teaches simulators and academics at the Introduction to Fighter Fundamentals course at Sheppard AFB in the Euro-NATO Joint Jet Pilot Training Program (ENJJPT). 'Tramp' was the family dog in the TV series 'My Three Sons,' starring Fred MacMurray. John owns a 1946 Luscombe 8E, his wife flies a 1946 Ercoupe 415C and they jointly fly a 1956 G35 Bonanza. Let's listen to a real expert...

"... I've been a flight instructor, civilian and military, since 1971. I'm convinced that final turn stall/spins occur due to two things:

1) lack of understanding of Angle Of Attack and
2) inadequate stall training.

"1) Angle Of Attack - a brief review: In a longitudinally stable aircraft with direct mechanical connection from the yoke to the elevator (all our aircraft), the AoA of the wing is directly proportional to the aft displacement of the yoke. Yoke forward = low AoA, yoke aft = high AoA, yoke in your lap = stall AoA.

"If you want a simple AoA gauge, pull the yoke all the way aft and paint the tube that goes through the panel: the inch closest to the panel gets painted red, the next inch or so gets painted yellow, all the rest gets painted green. If you never see red paint, you will never stall your airplane.

"What flight instructors really mean by 'keep the nose down' is 'keep the yoke forward.' In order to turn the airplane, you must pull back on the yoke or the airplane will descend. If you are trimmed for 80 mph in wings level flight and roll into a bank without pulling back on the yoke, the nose will drop and the airplane will accelerate.

"You also won't turn very well, because you aren't increasing the lift to pull the airplane around the turn (remember: airplanes turn with lift, and NOT with their ailerons or rudder).

"Admittedly, if you are using 30 degrees of bank or less, the amount of back pressure on the yoke is small ... but it's there. If you fly the pattern at 1.4 X stall speed for your weight and configuration, the airplane will not stall in a coordinated turn until 60 degrees of bank. That's a lot of leeway.

"For the record, in my G-model Bonanza at normal landing weight, 1.4 x Vstall = 78 mph. 80 is easy to read on the ASI, so that's where I fly [in the traffic pattern, maneuvering].

"2) Stall training: When an airplane is fully stalled, the elevator and the ailerons work backwards. Pulling back on the yoke in a stall makes the nose go down faster, not up. Putting in right aileron makes the airplane roll left, not right. (OK, so the engineers have cleaned up this last one a bit; many modern airplanes will roll either slowly right or at least not left with right aileron. Fly an older airplane and try putting in aileron while stalled and watch what happens). The rudder is the only control that still works same the way it did before the stall.

"Control reversal is what scares students (and CFIs) during stalls. Low-time pilots are still unsure of their ability to control the airplane; turbulence, configuation changes and new manuevers cause discomfort in students because the airplane responds differently and activates that fear of losing control. Full stalls, all the way to control reversal, scares the crap out of them because the airplane is now doing exactly opposite what they told it to do - it truly seems out of control.

"With training and experience, we learn that stalls, while backwards, are very predictable and controllable and, eventually, fun.

"Trouble is, not all students get that training and experience. Too many students are taught to recover at stall warning/buffet, and not after the stall break. If we let the student recover on stall warning, then he never sees control reversal, so he doesn't get so scared.

"But he also doesn't understand stalls
He pulls the yoke back and the nose goes up. The stall horn goes off/buffet occurs and he pushes the yoke forward and the nose goes down. Frightening but not terrifying because the controls worked like they always have.

"Scary as power-off stalls are, they are mild-mannered compared to a fully-stalled airplane at takeoff power. Power makes everything about stalls worse. More airflow over the elevators increases AoA and drives the airplane deeper into the stall. Torque, precession, P-factor and slipstream roll and yaw the airplane to the left and can over-power even the most mannerly ailerons.

"I've known too many CFIs who won't show aggravated stalls to their students because it scares them too much (it scares the CFI, not the student).

"Put all this together and we now have a stall/spin looking for a final turn to happen. Our young pilot goes out in his higher performance machine (one power-off stall during the checkout several years ago, none since). He's loaded a bit aft today and has a wind pushing his left downwind leg towards the runway. He flies well above stall speed and doesn't pull back on the yoke during the downwind to base turn. The nose drops during the turn and the airplane picks up speed, so he reduces power. Turning final, he doesn't pull back on the yoke again, so the nose drops and the airplane accelerates and he pulls a little more power. He's getting low but is distracted by the overshoot caused by the wind and the lack of turn rate. He increases the bank further and the nose drops more. He pulls back on the yoke but the nose doesn't come up (too much bank) so he pulls harder and puts in top aileron (feet are on the floor or using the footrests). Ground rush catches his eye and, in a moment of panic, he performs the one step of the stall recovery he remembers: full power.

"The airplane rolls and yaws left and our dead-man-walking seals his fate by pulling the yoke to the red and going full right aileron. His well-behaved airplane actually tries to roll upright with the aileron but the stalled wing and yaw from the engine spin the airplane neatly to the left. As the left wing drops, our hero is already dead; the airplane simply doesn't have enough altitude to recover.

"Fantasy? Nope, fact. My Luscombe will spin from a nose low gliding turn with feet holding the rudders neutral using only smooth back stick and power; the nose never gets above the horizon.

"My Bo doesn't quite spin under the same conditions but it's a pretty wild ride and definitely fatal at the wrong altitude. (I discovered these facts WAAAAAY up high above the ground).

"If you haven't done so lately, go out and get some stall training. Do all the stalls until they are as comfortable as your takeoffs. Do stalls at takeoff power and watch the horizon do strange things. Yes, do all this at a safe altitude and with a well-qualified instructor. But do it.

"Drill it into your brain and muscle memory that the yoke MUST come forward even if the nose is going down and that the RUDDER levels the wings and controls the yaw.

"While you're at it, fly around at 1.3-1.4 X stall speed for a while and get really comfortable in slow flight. Make sure you fly steady, coordinated turns with just enough back yoke to turn the airplane exactly like Mr. Beech designed it. Convince your gut that you can maneuver the airplane just fine to 45 degrees of bank with no worries at that speed. Once you are comfortable with all this, go back and do it all over again every year."

Hear from an FAA Route Check airman friend, Brian Harrelson. He offered this from our FAA. The FAASTeam - Safer Skies Through Education

June 2015--in the "Fly Safe" Campaign, the FAA is making a big push to get AoA indicators installed in General Aviation aircraft.

In its extraordinarily helpful December 2011 FAA clarification letter
, the FAA Small Aircraft Directorate explains that installation is a "minor alteration" on the vast majority of light general aviation aircraft.

Read more from pilots with General Aviation AoA Experience

Take a look at the accident summaries. Click here.


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