How to correctly change Estimated Enroute Time (EET) in an ICAO flight plan
We often are asked “why can I not change my Estimated Enroute Time to a number I like” when filing an ICAO conforming flight plan in Europe.
A couple of points are to be noted.
When filing IFR flight plans in Europe the IFPS does a parallel route time calculation against your aircraft parameters, the filed cruising speed and the filed route.
If your time differs against this calculation IFPS will reject the flight plan with the error message “TTL_EET DIFFERENCE > %, CALCULATED”
So unfortunately we at RocketRoute have to replicate their (IFPS) calculation.
Believe me the Airlines are not happy about the assumptions IFPS makes for their aircraft performance and have said so in many meeting with CFMU.
We calculate time on the climb speed you have entered in the aircraft paramaters (assuming you have atually done this, otherwise we have to use percentages.)
Then on cruise speed as filed and altitude.
Then we do wind correction with current GFS data forecast up to 5 days ahead.
This EET time appears in the EET field after you click REFRESH under the map or after you click SAVE if you have forgotton to do so it will be calculated in the background.
If you need to extend your flight time beyond this calculation ICAO provides two methods and we provide a third:
1) Slow down in flight
Example: KONAN/N0165F050 DCT KOK/N0140F050
Now you are telling IFPS that you are reducing speed at KOK and the EET will be recalculated according to that speed.
What Speed you actually fly in the end is a different question, but this should be a fair estimate.
2) Add an in-flight delay statement such as “STAY1/0010″
Then in field 18 you add the reason STAYINFO1/MANEUVERING
This example adds 10 minutes for Maneuvering
The text can literally be anything like STAYNFO1/VIEWING HOUSES etc.
This is commonly used by pipeline observers and the Military use this method extensively as you can see from the example here.
3) Add a little bit of EET time manually after clicking refresh without extreme values.
Small corrections will be retained by RocketRoute (We will check that you stay within IFPS limits though)