Is airspeed control in B777 fundamentally different than in a glider?

The news about the B777 accident at SFO is getting me confused. The news stories are constantly pointing to the Autothrottle not maintaining airspeed (and question if the 3 pilots in the cockpit were monitoring airspeed)but in all the aircraft I have flown airspeed is controlled primarily with pitch. Is there something fundamentally different about airspeed control in large jet aircraft? My experience is that pitch controls airspeed and power controls climb/descent, especially in the approach to landing situation.

Guy Acheson "DDS"

On Wednesday, July 10, 2013 7:13:56 AM UTC-7, wrote:
The news about the B777 accident at SFO is getting me confused. The news stories are constantly pointing to the Autothrottle not maintaining airspeed (and question if the 3 pilots in the cockpit were monitoring airspeed)but in all the aircraft I have flown airspeed is controlled primarily with pitch. Is there something fundamentally different about airspeed control in large jet aircraft? My experience is that pitch controls airspeed and power controls climb/descent, especially in the approach to landing situation.



Guy Acheson "DDS"

If you don't care how fast you are coming down yes you can control the airspeed with pitch. If you are trying to maintain a fixed glide angle (3 degrees for most airliner approaches) you will have to add power. IF the were maintaining the glide path with insufficient power there airspeed would have continued to decay all the way down final approach.

On Wednesday, July 10, 2013 4:28:54 PM UTC+2, Karl Kunz wrote:

If you don't care how fast you are coming down yes you can control the airspeed with pitch. If you are trying to maintain a fixed glide angle (3 degrees for most airliner approaches) you will have to add power. IF the were maintaining the glide path with insufficient power there airspeed would have continued to decay all the way down final approach.

Huh? AOA controls airspeed, even in airliners - you fly a constant AOA for the desired approach speed, with power varying to maintain glidepath: going low, you add power; high, you pull off a bit.

And sure, you can gain or lose a few feet by pushing or pulling, but soon you will have to add or remove power to compensate for the change in airspeed, and now you are destabilized.

Kirk
66

On Wednesday, July 10, 2013 9:13:56 AM UTC-5, wrote:
The news about the B777 accident at SFO is getting me confused. The news stories are constantly pointing to the Autothrottle not maintaining airspeed (and question if the 3 pilots in the cockpit were monitoring airspeed)but in all the aircraft I have flown airspeed is controlled primarily with pitch. Is there something fundamentally different about airspeed control in large jet aircraft? My experience is that pitch controls airspeed and power controls climb/descent, especially in the approach to landing situation.



Guy Acheson "DDS"

Portions of the pilots interview were posted and the right seat pilot said he assumed the auto throttles were on but they were not. He says he told the left seat low time pilot to increase speed and pitch but it was too late.

You are correct. It was what I was trying to explain - poorly. Pitch + Power = Performance.

On Wednesday, July 10, 2013 8:12:43 AM UTC-7, kirk.stant wrote:
On Wednesday, July 10, 2013 4:28:54 PM UTC+2, Karl Kunz wrote:



If you don't care how fast you are coming down yes you can control the airspeed with pitch. If you are trying to maintain a fixed glide angle (3 degrees for most airliner approaches) you will have to add power. IF the were maintaining the glide path with insufficient power there airspeed would have continued to decay all the way down final approach.



Huh? AOA controls airspeed, even in airliners - you fly a constant AOA for the desired approach speed, with power varying to maintain glidepath: going low, you add power; high, you pull off a bit.



And sure, you can gain or lose a few feet by pushing or pulling, but soon you will have to add or remove power to compensate for the change in airspeed, and now you are destabilized.



Kirk

66

On 7/10/2013 10:13 AM, wrote:
The news about the B777 accident at SFO is getting me confused.

Auto throttle or not, ILS or not, I think it's safe to assume that there
is nothing so fundamentally different about the B777 as to relieve the
pilots from their duty to be aware of their airspeed at all times,
especially while on final approach.

On Wednesday, July 10, 2013 10:48:21 AM UTC-7, Vaughn wrote:
On 7/10/2013 10:13 AM, wrote:

The news about the B777 accident at SFO is getting me confused.



Auto throttle or not, ILS or not, I think it's safe to assume that there

is nothing so fundamentally different about the B777 as to relieve the

pilots from their duty to be aware of their airspeed at all times,

especially while on final approach.

This is a great video on automation dependency and cockpit workload.

http://www.youtube.com/watch?v=h3kRE...e_gdata_player

I also suspect having 4 pilots involved ended up being less safe than just two.

Craig

On Wednesday, July 10, 2013 6:27:17 PM UTC+2, Karl Kunz wrote:
You are correct. It was what I was trying to explain - poorly. Pitch + Power = Performance.

Yeah, I figured it got garbled in transmission! ;^)

Cheers,

Kirk
66

Originally Posted by kirk.stant

On Wednesday, July 10, 2013 4:28:54 PM UTC+2,
Huh? AOA controls airspeed, even in airliners - you fly a constant AOA for the desired approach speed, with power varying to maintain glidepath: going low, you add power; high, you pull off a bit.

And sure, you can gain or lose a few feet by pushing or pulling, but soon you will have to add or remove power to compensate for the change in airspeed, and now you are destabilized.

Kirk
66

Spoken like a true F-4 Phantom alumni!

On Thursday, July 11, 2013 2:23:52 PM UTC+2, Squeaky wrote:

Spoken like a true F-4 Phantom alumni!

Guilty!

Rhinos rule - and they have audio AOA!

Kirk
66