need help to figure this out
Thread Starter
Joined: Jul 2008
Posts: 43
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From: New Delhi
need help to figure this out
An aircraft leaves A at 1400, flying at Mach 0.84 (OAT – 58° C). The ETA B is 1436 and the distance between A and B is 300 nm. At what time must a speed adjustment be made if the arrival time is changed to 1438:
A) 1426.5
B) 1427.5
C) 1428.5
D) 1425.5
correct answer is d ...
i have been able to figure out the true TAS=480 and the planned TAS =500
what to do next...is whats bugging me i tried all the speed and time stuff i knew but its confusing the living daylights outta me
A) 1426.5
B) 1427.5
C) 1428.5
D) 1425.5
correct answer is d ...
i have been able to figure out the true TAS=480 and the planned TAS =500
what to do next...is whats bugging me i tried all the speed and time stuff i knew but its confusing the living daylights outta me
Joined: Aug 2009
Aviation Qualifications: ATPL
Posts: 616
Likes: 57
From: GPS L INVALID
Either its too late for me and I cannot properly read the question or the question itself is incomplete - that depends on the speed adjustment! If the thing decelerates to 1 kts just before 1436 you can delay the arrival indefinetely... I dont get it.
Joined: Dec 2002
Aviation Qualifications: ATP+Mil
Posts: 3,985
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From: Where the Quaboag River flows, USA
This is one of those stupid, pedantic questions that CAAs think is required if pilots. Just pull the Mach back as soon as you know you need to adjust the arrival time and see how it works out. You will NEVER have to do this in real life.
GF
GF
Joined: Jun 2005
Posts: 954
Likes: 5
From: USA
Yes, when assigned a time to cross the oceanic transition point, adjust the speed so that the FMS estimated time over waypoint matches!
I think you guys are right. The speed increment was not provided in the question.
I think you guys are right. The speed increment was not provided in the question.
Nemo Me Impune Lacessit
Joined: Jun 2004
Posts: 4,103
Likes: 5
From: Chabanais, France
a speed adjustment
Reminds me of the old plotting question, "At what time and what position would you need to leave your existing track from A to B in order to arrive over your Diversion field, C, at the same time as you would have arrived over your original destination B. 30 marks! (GS of moving base etc.). So useful to me at the time, flying the BN2 Islander!
Joined: Oct 2009
Posts: 1,270
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From: UK
Hi shabez,
I think you'll find the ground speed was 500 kts.
You are missing the new Mach No. they will reduce to - else it's impossible.
the planned TAS =500
You are missing the new Mach No. they will reduce to - else it's impossible.
Last edited by rudderrudderrat; 12th September 2011 at 11:04. Reason: typo
Joined: Feb 1998
Aviation Qualifications: ATPL
Posts: 1,595
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From: Formerly of Nam
It a slightly practical question as sometimes one has to cross
a point at a certain time for ATC separation.
Of course the earlier the better. If left it too late one may be
waaay back on speed to make any real difference timewise.
I'd say what the bugger is asking you, is do you realise the
earlier the better out of the four answers provided? Just my
hunch.
a point at a certain time for ATC separation.
Of course the earlier the better. If left it too late one may be
waaay back on speed to make any real difference timewise.
I'd say what the bugger is asking you, is do you realise the
earlier the better out of the four answers provided? Just my
hunch.
