Flight Monitoring

Question 1

Planned ground speed 90 kts

Take off at point A = 12:05
ETA at point B = 12:42
ETA at point C = 13:02
A to B = 55nm
B to C = 30nm
ATA at point B: 12:47
What is the actual ground speed and new ETA to point C

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Answer 1

ETA 13:10

Use Speed Distance Time triangle

Planned ground speed 90 kts. 90 kts is 90 nm in 60 minutes. To determine the original ETA for 55nm
90 kts / 60 mins = 1.5nm per minute
55 nm distance / 1.5nm per minute = 36.66 (37 minutes)
12:05 + 37 = 12:42
ATA 12:47, so 5 minutes slower.
55nm / 42 mins = 1.309nm per min
1.309 x 60 minutes = 78.57 (79 knots G/S)
Knowing ground speed is 1.309 per minute, distance from B to C is 30nm
Speed distance time triangle, distance divided by speed = time
30 / 1.309 = 22.91 = 23 minutes.
12:47 + 23 minutes = NEW ETA: 13:10

Question 2

What is the formula to determine the heading change required to get to destination when off-track

Answer 2

(Distance off track (nm) / Distance gone (nm)) x 60
+
(Distance off track (nm) / Distance to go (nm)) x 60

DOT / DG x 60 + DOT / DtG x 60

Question 3

20nm from your destination, crusing at 77kts ground speed at 5000ft, you need to be at 2000ft 5nm before the destination. Calculate the RoD

Answer 3

256 ft/min

Calculate how much altitude needs to be lost; 5000ft - 2000ft = 3000ft
Calculate the distance you have to do this in.
We want to be at 2000ft 5nm from destination. Destination is 20nm away. 20 - 5 = 15nm
Calculate how much time; cruising at 77 kts. This is same as 77nm per hour
77nm / 60min = 1.28nm/min
15nm / 1.28nm/min = 11.7 minutes
Calculate altitude to lose over 11.7 minutes
3000 / 11.7 = 256ft/min