Re: [SystemSafety] Chicago controller halts Delta jet's near-miss....

From: Klaus < >
Date: Mon, 29 Jun 2015 09:15:12 +0200

Dear all,

I am a commercial pilot, flying for a european airline.

A little about basics

Yes , Pilots are empowered to do everything necessary for the safety of their flight.

HOWEVER......if it means deviating from established rules and procedures (there
are many) , a *very* good reason is required, like avoiding danger to the aircraft.

Just say : mayday mayday mayday ..... and the sky is -basically- yours.

No: it doesnīt happen often.
Yes: the whole system would collapse if everone did it at the same time

About takeoff

If you fly VFR, visual flight rules, at an uncontrolled clearace for takeoff
or landing is either required or given, for the simple reason that there is no air traffic
controller who would take care of things.

If you fly IFR, like the vast majority of airline flights do, then you definitely need
a clearance for takeoff as well as for landing. Think airports like Chicago, Frankfurt,
London Heathrow: a clearance is most definitely required.

About communications

Yes, there are protocols to follow in aviation communications, neatly layed down
by ICAO, in various places:
Annex 2............... interception , ground marshalling, com-failure: basic rules
Annex 10 ............ technical specifications of radio systems for voice + data
Doc 9432 ............ Manual of Radiotelephony (= how to say what you mean) Sovereign States.....can and do modify these.

Blocked communication
...due to two or more stations sending at the same time... does not have to be a problem. Technically , radios could contain a device that
inhibits transmission if other transmissions are detected. Solution is known for decades, not implemented. :-(

Callsign confusion
... has been regonized as a problem decades ago. It can occur when two aircraft with
nearly identical or very similar callsign are on one frequency. It can be alleviated by
systems that check the flight-plans of all airlines/flights, and re-assign numbers / letters
as necessary. State -of-the -art callsign deconfliction between and within many european
airlines is done by Eurocontrol.

Then, ICAO manual 9432 specifies: An aircraft shall not change its type of call sign during flight except when there is a likelihood that
confusion may occur because of similar call signs; in such cases, an aircraft may be instructed by an air traffic control unit to change the type of its call sign temporarily.

Another factor is, of course, the quality of the communications medium used. Hi-Fi listening
pleasure is not what VHF radio communications is all about : itīs about saving bandwidth
to get as many (analog) VHF communications channels as possible into the part of the
frequency spectrum reserved for aeronautical telecommunications....

I hope that this clears up some issues, and that I got most of my post right.

Klaus Sievers

Am 29.06.2015 um 07:10 schrieb Peter Bernard Ladkin:
> Hash: SHA256
> On 2015-06-29 01:28 , Les Chambers wrote:
>> Peter Can I clarify your assertion? (This is a message [3] style communication) Do your words
>> below assert that a pilot (as "enshrined in most countries' law ") is empowered to take off
>> without clearance from ATC?
> What do you mean by "empowered"? It is not a term I recognise from aviation procedures.
> Pilots take off without ATC clearance all the time. I'm sure half the takeoffs I have done were
> without clearance. All the flights I have been on in Germany except one were without takeoff
> clearance. An ATC clearance for takeoff is not necessarily part of operating procedures.
> The pilot in US, UK and German law (and probably Australian although I haven't checked) is able to
> undertake any action necessary to ensure the safety of the flight. A pilot who takes off without a
> clearance where a clearance is part of the procedures under which heshe is operating will usually be
> asked to talk to the regulator in the US, UK and Germany. If the regulator is not convinced that
> it was necessary to ensure the safety of the flight, sanctions may ensue, up to loss of license.
> It is not unknown, although rare, for pilots doing odd things in the US to be prosecuted by law
> enforcement personnel. "Reckless endangerment" or something similar is often charged in such cases.
> I am not sure how enlightening it would be to discuss basic aviation law at this level. This is
> basic "intro to flight" material such as prospective pilots have to understand at their local
> flying club during ab initio flight training. In the US, prospective pilots have to read and
> understand FAR Part 91 (14 CFR 91), available from
> . In the UK, it's CAP 393, available
> from
> Both of these publications concern the rights and responsibilities of pilots. The responsibilities
> of ATC are not included in these publications. Here is the document which I believe describes ATC
> phraseology and procedures in the US The
> general responsibility of ATC is to ensure separation between participating aircraft, and to
> effect separation as far as practicable between participating aircraft and others. "Participating"
> means aircraft under instrument flight rules. "Non-participating" aircraft will be flying under
> visual flight rules, and such aircraft may or may not be talking to ATC. Those that are are said
> in the US to be engaged in "flight following". Some of those that are not may have no radio.
> Prof. Peter Bernard Ladkin, Faculty of Technology, University of Bielefeld, 33594 Bielefeld, Germany
> Je suis Charlie
> Tel+msg +49 (0)521 880 7319
> R6kELD+CiDXmQjNfKtu1eaoj9HMuJUHSzE6noqXM6gxxGmHkJWz02AHkWEiTS6Sl
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