Compass updates
04-03-2015 | 07:53 AM
#6541
Line Holder
Joined: Nov 2012
Posts: 83
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At 35,000 ft, 250 KIAS is approximately 430 KTAS. And the speed of sound at 35,000 on a standard day is 574 knots vs. 661 knots at sea level.
IAS and TAS both decrease with altitude with IAS decreasing at a higher rate than TAS. So as you climb AOA will increase to provide the same amount of lift in a constant MACH climb. At least that's what I think...
IAS and TAS both decrease with altitude with IAS decreasing at a higher rate than TAS. So as you climb AOA will increase to provide the same amount of lift in a constant MACH climb. At least that's what I think...
04-03-2015 | 07:54 AM
#6542
Gets Weekends Off
Joined: Jun 2013
Posts: 806
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You must've flown into an inversion layer. 
Here's what I saw this morning...
FL225: Mach .70, TAS 431, SAT -22C
FL275: Mach .68, TAS 412, SAT -33C
FL310: Mach .79, TAS 470, SAT -42C
FL350: Mach .79, TAS 462, SAT -49C
FL370: Mach .79, TAS 451, SAT -54C
The speed of sound measured by the Mach meter went from 616kts at FL225 to 571kts at FL370.
In a climb at constant Mach, decreasing TAS, decreasing SAT (until the stratosphere).
Here's what I saw this morning...
FL225: Mach .70, TAS 431, SAT -22C
FL275: Mach .68, TAS 412, SAT -33C
FL310: Mach .79, TAS 470, SAT -42C
FL350: Mach .79, TAS 462, SAT -49C
FL370: Mach .79, TAS 451, SAT -54C
The speed of sound measured by the Mach meter went from 616kts at FL225 to 571kts at FL370.
In a climb at constant Mach, decreasing TAS, decreasing SAT (until the stratosphere).
04-03-2015 | 08:13 AM
#6544
Living the Dream
Joined: Sep 2013
Posts: 1,795
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It's true your AOA increases with altitude, but in the context of this question... May be underthinking this, but would your angle of attack decrease in speed mode so as to maintain the same speed in the climbout? That's why you occasionally need to reduce the speed or go to VS as you near your level-off - to get the nose back up.
04-03-2015 | 09:16 AM
#6545
Gets Weekends Off
Joined: Jan 2015
Posts: 458
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From: E-175
It's true your AOA increases with altitude, but in the context of this question... May be underthinking this, but would your angle of attack decrease in speed mode so as to maintain the same speed in the climbout? That's why you occasionally need to reduce the speed or go to VS as you near your level-off - to get the nose back up.
But yes, I correct myself. (late night half asleep thinking got me on my response last night)
IAS and CAS decrease, TAS decreases (if temp decreases). FAA Pilots Handbook of Aeronautical Knowledge. See this link, top right paragraph of page 4-41 if it doesnt show it right away.
The question remains in my mind about the AOA. Assuming constant weight (obviously not possible) As TAS and IAS/CAS decrease, AOA would need to decrease to keep speed up as airspeed falls off. However, I dont know how significant fuel burn adds complexity to this. Maybe its near constant
https://books.google.com/books?id=1H...%20aoa&f=false
04-03-2015 | 09:24 AM
#6546
Gets Weekends Off
Joined: Feb 2007
Posts: 3,045
Likes: 1
From: FO
As speed decreases, AOA will need to increases to maintain the same amount of lift.
If airspeed is constant and all the changes is altitude. A higher altitude will require a higher AOA, due to the density of air changing.
If airspeed is constant and all the changes is altitude. A higher altitude will require a higher AOA, due to the density of air changing.
04-03-2015 | 09:40 AM
#6547
Gets Weekends Off
Joined: Feb 2007
Posts: 3,045
Likes: 1
From: FO
It's true your AOA increases with altitude, but in the context of this question... May be underthinking this, but would your angle of attack decrease in speed mode so as to maintain the same speed in the climbout? That's why you occasionally need to reduce the speed or go to VS as you near your level-off - to get the nose back up.
The thing that governs climb rate in an aircraft is excess thrust available over that is required for level flight at a given speed.
The reason you may have to reduce speed in a climb up to altitude is that the thrust available is insufficient to maintain your desired climb rate, altitude, and airspeed at the same time.
04-03-2015 | 03:27 PM
#6548
Gets Weekends Off
Joined: Oct 2014
Posts: 225
Likes: 0
From: Bent Over
Anyone got a seniority list? How junior did the award go? Last alternate?
04-03-2015 | 03:32 PM
#6549
Gets Weekends Off
Joined: Nov 2011
Posts: 4,564
Likes: 24
most jr CA is a 10/14 hire
04-03-2015 | 04:14 PM
#6550
Line Holder
Joined: May 2013
Posts: 52
Likes: 0
FWIW, nobody will ever, ever, ask you that Mach question outside of the test.
Not on your interview. Not in training. Not on IOE. Not on the line. Not in recurrent. Not ever. :-)
Keep it above green dot, below V/MMO and you'll be fine.
Not on your interview. Not in training. Not on IOE. Not on the line. Not in recurrent. Not ever. :-)
Keep it above green dot, below V/MMO and you'll be fine.
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