Departure Call IFR
 

What's the norm giving a dept call IFR, use the GPS est for the next reporting point or do the maths using your flight plan est.

The GPS estimate won't be correct until after TOPC and you've reached your cruise speed. Therefore, the estimate from the log will probably be more accurate.

Nevertheless, you won't find it particularly difficult to come up with your own rules of thumb to correct GPS ETA for lower speed during climb.

If you've got a performance database on your fms and you've told it your cruise altitude and the winds aren't too outrageous, then the fms eta at the next waypoint will be all good

Maths I'd say would be best, or if you have a general rule of thumb, say each thousand feet adds an extra minute to the ETA on your GPS? Either way really is fine as long as it's accurate enough.

If you get it outrageously wrong, expect
"system estimate is XX, advise" ;)

The GPS (GNSS) estimate is rubbish. It's based on your current g/s. Hence why you'll hear the rather ragged voice on the other end of the line saying "report amended estimate at top of climb"...(i.e. learn to use a prayer wheel).

The 'new generation' of pilots don't know their arse from a hole in the ground. And it's all our generations fault. We taught them.

.. or use AvPlan EFB and just read it off - it displays the ETA based on the time taken to climb and cruise and not an ETA based on a GPS groundspeed..

Hempy, I didn't & don't teach them that garbage

An estimate based on the GPS ETA with suitable subtraction amendment for distance to be flown. However, if it looks like you are going to be well out, for example due to high local winds on departure but not expected for whole flight, one can always qualify the departure report with "...will update at top of climb."

I should add that an accurate ETA is as long as a piece of string for the multitude of factors that enter into the equation. I used to use a company generated flight planner that was remarkably accurate for the aircraft that we flew. Time and time again I was quite amazed at how accurate it was at generating the ETI for that first leg, probably more so that the GPS with suitable amendment. Regrettably we can no longer use it due to the almighty upheaval in waypoint names by Airservices (God rot their cotton socks for that).

I think the main point is that the GPS ETA just after departure is always inaccurate by a long shot, unless you happen to maintain exactly the same GS in the cruise as you do in the climb, or the leg is very, very short.

It's sad that this is even a question.

Yes. Even more sad is a couple of the replies.

What about people who say "pending clearance?" Who's teaching them that

HF is always a joy! :}

If you get your estimate wrong there's a very simple fix. "Revised Estimate...." :ok:

'pending clearance' was intially a Q-Link wank that other pilots heard and thought 'that sounds neat, I'll use that too'.

Not realising how ridiculously stupid and redundant it was in the first place, nor the fact that AIP states that the departure call includes the 'intended cruising level' regardless of whether a clearance is required or not. :ugh:

Thanks
 

Thank you for your valued comments, and just for knockers it must be a great life you have being perfect.

I'm not perfect, but I try to get things right by actually reading the AIPs.

I would rephrase that to say, forget about all this ETA crap and reflect on how the appreciation of great knockers can make your life perfect!

Yes, the world would be a lesser place were it not for great knockers! :ok:

Dr :8

To keep it really simple for piston ops, take 2 minutes off the indicated GPS ETA for your next waypoint, and revise at TOPC if required. You still have the AIP buffer anyway.

What is a WIzz Wheel anyway?