×
##### PPL Video Lectures (10 Jul 2020)

PPL Video Lectures covering Aerodynamics, General Knowledge, Performance, Meteorology And Navigation are now available through our website see front page for details.

× Welcome to the CPL Performance question and answer forum. Please feel free to post your questions but more importantly also suggest answers for your forum colleagues. Bob himself or one of the other tutors will get to your question as soon as we can.

## ETI from departure to destination

• jukzizy
• Topic Author
• Away
• Posts: 154
• Thank you received: 0

### jukzizy created the topic: ETI from departure to destination

Travelling A-B is 168 NM
Track 144* t
ARFO 200/40KTS
TAS 140 KTS
VARIATION 9*E

Calculate the ETI from departure to destination:

Track 144-9= 135*M
Distance 168
x-wind 36 kts
Etas 135 kts
G/Speed-135-17=118 kts

Time= Dis/speed
= 168÷118=1.423*hrs×60= 85.42/85 minutes

Sir can you check if I did this question without missing anything and check if the amswer is makesens

Please Log in or Create an account to join the conversation.

• Posts: 154
• Thank you received: 25

### Carello replied the topic: ETI from departure to destination

I get a G/S of 114 kts

ARFOR wind directions are True not Magnetic.
Rework the problem with a magnetic wind direction and a magnetic track.
You can't mix apples with oranges; if you do, you get a fruit salad.

Please Log in or Create an account to join the conversation.

• jukzizy
• Topic Author
• Away
• Posts: 154
• Thank you received: 0

### jukzizy replied the topic: ETI from departure to destination

which means :
Etas 136kts-22kts=114kts?

Time= distance/speed
136/114
88 minutes?

Please Log in or Create an account to join the conversation.

• John.Heddles
• Offline
• ATPL/consulting aero engineer
• Posts: 454
• Thank you received: 42

### John.Heddles replied the topic: ETI from departure to destination

Several points to note -

(a) one can't mix deg T and deg M with a significant variation. You have all the information in deg T so there is no need to convert anything to deg M. Makes no difference to the answer if you work all in magnetic or all in true - your call if you want to do more calculations than you need to do. You just can't mix the two.

(b) answer on the Dalton or Jepp is the same (as you would expect). G/S =114 and HDG = 157-158T (heading is not required for the question)

(c) suggest you always run the ETAS calculation on the Jepp, regardless of the drift angle. Gives you the mathematically correct answer and you always use the same technique rather than setting yourself up for another decision and potential for error.

(d) perhaps you meant to type in 168/114 in the previous post ?

Engineering specialist in aircraft performance and weight control.

Please Log in or Create an account to join the conversation.

• jukzizy
• Topic Author
• Away
• Posts: 154
• Thank you received: 0

### jukzizy replied the topic: ETI from departure to destination

yes

Please Log in or Create an account to join the conversation.

Time to create page: 0.203 seconds