The puny little DH8-300 had something rather similar but more refined than a pure AOA indicator installed. On the left side of the horizon, there was an indication similar in looks to a GS display with a diamond. When centered, the aircraft was at 1.3 Vs = an appropriate approach speed; higher or lower speeds were shown by the diamond moving up and down.

This was a beautiful and technically rather simple fallback alternative, should the airspeed measurement give grounds for doubting its reliability. One would think that with modern EFIS aircraft this might be easily programmable and a little corner on the PFD (maybe to the left of the ASI, similar to how the VSI is often crammed beside the altimeter tape) might also be found to show this.

HUD
 

I think it's standard equipment in all Russian/Ukrainian designed Transport Aircraft.

Mandatory informations, according to Gilbert KLOPFSTEIN :

At the time of the AF447 crash, because early indications were consistent with a deep stall from a condition of inoperative ASI, I was very curious whether that particular plane was fitted with an AOA indicator.

If I recall correctly, AOA is not available on the primary flight displays, but there is another screen (I want to say FMS, which I thought most unintuitive) which can be selected into a display mode that includes AOA.

I'm not a pilot myself, but it seems to me that with proper training in its use, an easy-to-read AOA display could be very helpful for:

(1) managing the ASI inoperative situation

(2) avoiding upset in general

(3) maneuvering to recover from a gross upset

The Tristar had one for final approach. The speed readout went to Alpha after Land Flap selection (and some other parameter, my memory fails me) so instead of chasing Vref you flew to the Alpha.

Loved it, especially in a hooligan of a wind.

I'm sure 411A would have loved to talk about that one, especially in light of recent accidents. Poor guy would roll over in his grave if he heard about Asiana 214...:(

Can you elaborate on that a bit Moosp ?


How did the airspeed display actually change ?


Very interested.

AOA
 

Both American Airlines and Delta Air Lines have AOA indicators on their PFD's. 777 & 737NG. These two airlines were responsible for Boeing' making ths a customer option.

In the AF447, Thread #6, there was considerable discussions regarding unreliable air speed and AoA. There was a post by A33Zab that provided the following information regarding the Airbus BUSS design. It is standard on the A-380 and optional on other Airbus aircraft such as the A-330.

http://i1166.photobucket.com/albums/...psf391b3dd.jpg
BUSS DESIGN
The BUSS is displayed on both PFDs. It is based on Angle Of Attack (AOA) information, and
enables to easily and safely fly the aircraft without any valid airspeed indication. The BUSS
enables to fly the aircraft in the entire flight domain while observing the design limits.
The BUSS scale is divided in three color-coded areas:
• In the green area, the aircraft has normal margin towards ultimate limits i.e. VMO/VFE for
upper limit and stall for lower limit
• In the upper and lower amber areas, the aircraft has limited margin towards ultimate limits.
Flying in the amber area is acceptable for a limited period of time but it should be avoided
• The red areas (FAST or SLOW) must be avoided.
The BUSS is tuned using the aircraft’s aerodynamic model with speed brakes retracted.
When the BUSS is active:
‐ The altitude indications are based on GPS data. Two amber dashes cover the last two
digits because the GPS altitude is less accurate than the barometric altitude
‐ The vertical speed indication is no longer available.
FLYING TECHNIQUE
The PF adjusts the pitch and thrust, to maintain the AOA in the green area of the speed
scale.
For approach, the flight crew should perform a stabilized approach.
The flight crew should change the aircraft configuration with wings level.

Turbine D
There was no BUSS on AF447 (optional)
Could you confirm BUSS is independant of ADIRU?
Why did Airbus put that AoA ref in the speed scale maintaining pilots in the idea they have to fly speed and not AoA to be stall safe? I know pilots are supposed to be stupid and often are ignorant and stupid, but they may learn ONE thing since Orvilles , Wright and Ader : that stall is not loss of speed but bad AoA.

Couldn't we definitively go to inertial HUD? Royalties?

BUSS
 

BUSS is not useable above 22 or 24000 ft (thks to correct these values)

@ roulishollandais

1. I know there wasn't a BUSS installed on AF447, I just referenced the source of the photo and information I posted.

2. I attempted to provide an answer to the original question of the topic.

3. The BUSS becomes active on both PFDs when all ADRs are switched off. All ADR data is removed. The AoA signal is fed into the IR part of the ADIRU, the IR part is available even with air data off.

4. You need to converse with Airbus regarding philosophies of their BUSS design regarding speed and AoA as related to pilot intelligence levels as well as HUD displays.

@ VNAV PATH

In September 2009, Airbus sent out a notice to operators that the BUSS shouldn't be used above 25,000 feet. I am not sure of the reason behind this or if this has change in more recent times.

AirRabbit has summarised it best.

It costs money to fit, if it is an option.

It would mean extra training=it costs money.

Therefore only the more enlightened fleet managers will FIGHT TOOTH & NAIL to have it provided for their troops.

Until then, be prepared for lots more CFITs by otherwise perfectly serviceable aircraft and their unwitting SLF.

"Tombstone Imperative" again, it's great book, needs reading by those in the positions of power.

This subject has been discussed ad infinitum on the AF447 threads.

I am a big AoA proponent, but for "normal" heavy use, it is most likely not to be used for approach and such. The "simple" airspeed values from the FCOM or whatever are sufficient. IMHO.

In the case of AF447 and some other incidents, think Asiana, a reliable, inertially based flight path marker would seem to offer more info to the pilots. With a HUD, it would be even more helpful.

Just think about a display that showed your flight path starting to go down when you have been pulling back on the stick for a minute or two!!! Duhhh? Whaz happening?

So I lose all air data, including AoA, but I still have an independent doofer that shows my flight path WRT the local level and pitch lines for a few degrees above and below. Used it a time or two when the pitot-static stuff went south. No big deal, and basic attitude and throttle settings agreed with the expected flight path marker.

Turbine D post #30

Looks like there is an intrinsic error in the description of SLOW part of the tape, i.e.

"Red lower area corresponding to CAS > VLS"

The image below would seem to have the correct description.

http://oi43.tinypic.com/2ewjekj.jpg