Cool 737NG HUD Pics

[Subs 0]

In civilian aviation military style AOA gauge somehow never rose to prominence. Perhaps (my speculation)civilian pilots must pay much closer attention to aircraft speed (Boeing, airlines SOPs strictly require it) than their military colleagues

Thinking about it more, I guess you're right. I was just curious about it during a light bulb moment, when I realised the purpose of a HUD is the same, aerdynamically military and civies fly the same way, the pilot has the same responsibilities during landing - yet the landing techniques are so different. I find it interesting that there is so much common ground, but different techniques are used. I guess that was the point I was trying to make - my wording went a bit astray in my earlier post :)Subin.

[Spin737 102]

Probably can but I fail to see why this 737NG setup is somehow "inferior". Clearly they do have FPV and while they don't have an AOA gauge they have perfect controlover speed which is an indirect way of controlling AOA. In civilian aviation military style AOA gauge somehow never rose to prominence. Perhaps (my speculation)civilian pilots must pay much closer attention to aircraft speed (Boeing, airlines SOPs strictly require it) than their military colleagues. "Whatever the IAS" has no place in civilian aviation.

Top right corner of the HUD and the PFD in the first picture is the AOA. I believe the AOA is standard in the HUD and an option on the PFD on the NG.

[FloggedHorse 1]

Probably can but I fail to see why this 737NG setup is somehow "inferior". Clearly they do have FPV and while they don't have an AOA gauge they have perfect controlover speed which is an indirect way of controlling AOA. In civilian aviation military style AOA gauge somehow never rose to prominence. Perhaps (my speculation)civilian pilots must pay much closer attention to aircraft speed (Boeing, airlines SOPs strictly require it) than their military colleagues. "Whatever the IAS" has no place in civilian aviation.

Your speculation is partly incorrect. I doubt your theory of "Whatever the IAS" would wash with many military pilots. Here are some thoughts I have regarding the difference of the two approachs to final approach management:

• Speed and alpha directly linked together as a function of angle of bank and weight. After all the wing must produce enough lift to balance the weight in the various configs and attitudes. Basic aerody theory here.
• Fast jet aircraft often recover in formations and recovering a high voulme of aircraft to an airfield is of utmost importance. So tight circuits is the order of the day. Tight circuits results in higher angles of bank to get around base. Up to 60 degrees of bank can be used whereas a Boeing or Airbus type would rarely use more than 30 degrees of bank.

• Fighter aircraft are often much more sensitive to changes in alpha as they have a more aggresive (thinner) aerofoil to deal with supersonic flight. They are also reasonably light in comparision to the civilian jet counterparts therefore are suffer more from changable wind / turbulent conditions.

• Many military jet aircraft are much more concerned about deck angle on touchdown due the fact that many are fitted with hooks for either naval ops or emergency situations. Rather then grease the jet on for passengers comfort many fighters simply reduce the rate of D enough to place the gear within limits and get the wheels on the commence braking. Fighters are too light to carry heavy deuty brake units around and most do not have reverse thrust / spoilers (although some do). As a result of all of this it is important to land at the correct alpha as this will result in ideal cable parameters and as alpha and speed are linked (via angle of bank and weight) the correct approach speeds will be attained.

In practice the two circuits flown are vastly different however with the same result. To see it in practice, open your 747 and fly a tight circuit utilising the auto-throttle. Have the velocity vector on your PFD also. Dial in Vref plus additives and watch carefully how the attitude and velocity change around base whilst maintaining the same speed. The attitude will also 'raise' towards the pitch limit bars (yellow bars on PFD). Now to fly the way a fighter would simply fly another circuit (all manually this time) holding a constant alpha. You will note the speed will increase around base and angle of bank is introduced and the attitude will hold constant with reference to the pitch limits bars. Much more throttle manipulation is required in this case also. No person here was claiming either method inferior Subs was simply pondering the difference. Hopefully my rambling here will point out some key differences. Both methods result in safe landings and that is goal!!!Tim

[michal 44]

I doubt your theory of "Whatever the IAS" would wash with many military pilots.

This is not MY theory, I was replying to someone else about this "theory". Perhaps you are replying to the wrong guy or got mixed up who said what.