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-   -   Clearances that are impossible to accept (https://www.pprune.org/atc-issues/198511-clearances-impossible-accept.html)

the_hawk 17th November 2005 11:27


VFR by Law means clear of cloud and in sight of the surface.
But there's no need to be in sight of the surface for the whole VFR flight, right?

threepointonefour 17th November 2005 12:28


VFR by Law means clear of cloud and in sight of the surface.
Not true. It is possible to fly VMC above 8/8 cloud under Visual Flight Rules.

This is just one of many inaccuracies in many of the posts above.

Gary Lager 17th November 2005 13:09

JC - file a CHIRP report. I should have thought of that sooner.

FF - the GLAA (Gary Lager Aviation Authority) advises it's pilot (guess who) never to assume that a cleared level anywhere in the world is safe.

Never assume, check!


I say keep all departures and arrivals procedural. That way we only have ourselves to blame
I say that's a bit harsh (sarcasm, possibly?) - ATC do a superb job and provide, in the UK and some parts of Europe at least, an excellent service.

But that's all it is, a service - designed to improve Air Navigation Safety, and help us operate more efficiently. As long as we pilots realise that, we shouldn't fall into the trap of ignoring its limitations.

RYR-738-JOCKEY 18th November 2005 18:42

GARY, YOU ARE WRONG!

And I have the evidence. I have done a bit of research.
Directly translated from norwegian, so excuse my english:
"The ATCO shall for an IFR-flight under Radar-control, give clearances that provides the required terrain separation minimum. As of Sept 29th 2005, this is also a requirement when the ATCO gives an IFR flight direct routing away from an ATS route. In addition, the responsibility of correcting for temperature will in both of the above mentioned examples be transferred to the ATCO.
This is done to bring the norwegian regulations in line with ICAO's Doc 4444 PANS-ATM. The terrain separation will be provided until the aircraft will reach such a point where the PIC will provide terrain separation and temperature correction himself."

Thank you.

Now....beer time::}

Gary Lager 18th November 2005 19:23

Decided not to PM that one, then?

Hooray, I can continue doing the crossword whilst descending below MSA, (as long as I am on a radar vector!) safe in the knowledge that I cannot possibly hit terrain, and even if I do, it's not my fault!

Yippee! Thank you for making my days at work so much easier.

PS I'll think you'll find MATS Pt1 (UK ATC Manual) says the same thing - and that doesn't change my argument.

If you are Norwegian (or just a non-native english speaker) then I will give you a break; an ATCO's responsibility to provide safe vectors/descents (as required by regulation) and a pilots responsibility to the aircraft in ensuring those vectors/descent clearances are safe are not the same thing - and are not mutually exclusive.

Perhaps the confusion arises because we use the word 'responsible' to mean merely 'given the task of' as well as in the legal, overriding, 'in charge of' sense.

As a little aside, I refer you to an incident involving a B737-200 near Cape Town, S. Africa in July 1993 (sorry I can't be more specific).

The aircraft was being vectored for ILS 01 and was cleared down to 4500' MSL, then 3500' MSL just as they passed what was the actual minimum safe vectoring altitude (6500'). The FO remarked "...that seems a bit low...", to which the Captain replied "...on radar - it's OK!".

The first GPWS warning sounded at approximately 15 seconds to impact with a 5211' mountain. The aircraft managed to climb away safely.

They were on radar vectors. Do you see what I'm getting at?

I stand by what I have written to you previously.

stue 19th November 2005 12:37

Iv got to say, im not botherd what service im geting from an ATCO (speaking only as a PPL), be it a clearence, instruction, advise or what ever, there is no way that im not going to check that i can comply with it safely, if at all.

At the end of the day, its ME that isnt going to get to go to the pub if I flew my plane in to the ground. Even if its the ATCO's job to give me terrain clearence. I want to be happy that i will make it over that terrain before i will acept it.

ATCO's do a fantastic job hovever, i take my hat off to you (if i was wearing one :D ) but as P1 its my decision to conduct the flight safely, so i will check and clearence given.

:D

Timothy 20th November 2005 10:18

Another point in all this is that the ATCO is thoroughly conversant with his or her local area and will be aware of every hill and every obstruction, including temporary ones.

The (non-based) pilot will be relying on documentation which may or may not be accurate and up-to-date, may or may not be easily legible (particularly in bad weather or at night) and he or she may or may not mis-read the documentation due to tiredness, under-preparedness or unfamiliarity with the format.

Given that imbalance does it not behove the controller to provide a service which at the very least is possible with repect to obstacles and ideally is completely safe?

Pierre Argh 20th November 2005 13:12

First Point: Terrain Clearance... see other threads, this is a subject where there is variation across the world between service providors (although common sense would indicate it should be standard)

Given that imbalance does it not behove the controller to provide a service which at the very least is possible with repect to obstacles and ideally is completely safe?
Second Point: In the UK the PIC is responsible for Terrain Clearance under all ATC Services except Radar Control... there is talk above about "when receiving vectors"; sorry it is still the PIC's responsibility, however in many/most cases regulations will not allow the ATCO to provide vectors below a safe altitude either in toto, or unless the pilot has been reminded of his responsibility.

Finally, I am concerned that there are pilots here who don't actually understand fully what VFR means... i.e. it's not just "Clear of Cloud, in sight of the surface" and I suggest you take a look at the rule books again before you next fly?

Timothy 20th November 2005 18:52


Finally, I am concerned that there are pilots here who don't actually understand fully what VFR means
A perennial problem arising out the fact that licence privileges are at odds with the ICAO definition (in the UK, but not in many other countries) and that there are loads of pilots who are now in IFR only operations who have never really flown VFR (beyond ab initio in the circuit).

One of the problems is that some of the latter later have rings all the way up their sleeves and end up in a management and/or regulatory capacity despite a complete lack of knowledge or understanding of flying outside controlled airspace.

Tweety 27th November 2005 21:52

as was said on another thread, if a pilot has any doubt as to the safety of a clearance or not being able to comply with a clearance then they should inform ATC ASAP as this is when accidents can happen

yarrayarra 28th November 2005 12:43

Tweety - with you.
But getting to the basis of the original post, I think the ATC hasn't done a real flash job in providing an acceptable clearance. I remember my early days as a student pilot and I thought ATC was like the police or God. Whatever they said goes. Wouldn't be the best of outcomes in marginal weather where an inexperienced VFR pilot trying to comply with a clearance conducted a CFIT. Here in OZ the ATC would be strung up.


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