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From time to time, I receive request from other pilots about flight planning, and one recurrent question is “how to avoid this controlled airspace ?”. Circumnavigating and fleeing controlled airspace seems to be the favorite activity of many light aircraft pilots. Why is that ? I’ve some ideas…

In Europe, it’s going VFR through major terminal maneuvering area (TMA) is hardly possible. From an operational point of view, high-density IFR and VFR do not mix really well. That being said, there are not so many of such TMAs. In Switzerland we have Geneva and Zuerich. France has Paris and Nice, Germany has Frankfurt.

Apart from such mammoths, every piece of controlled airspace can be crossed rather easily, given that your phraseology is correct and efficient. My favorite example is the huuuuuuge TMA of Lyon, in eastern France. While not being a major airport, Lyon St-Exupéry is rather busy. Its TMA is more than 50 miles wide and from north to south, it is over than 70 miles long. If you know the route, and the appropiate frequency, crossing over the two runways is really not a problem.

You don’t know what to say to the controller, or don’t know what to expect as an answer ? Here’s a short refresher…

Let’s start by calling the controller. You should find the appropriate frequency on your chart, together with the description of the airspace. Once you get in contact, simply state your request, but don’t give the details of all your flight. Something like the example below should be suffcient:

“Lyon Approach, good morning, HB-XXX”

“HB-XXX, Lyon Approach, go ahead”

“HB-XXX, DA50, VFR From Geneva to La Rochelle, overhead CBY VOR at 5′500 ft, request crossing your airspace, route LSE and then west.” If your transponder is transmitting, you can also indicate the code you’re using. This is a quick example, probably not 100% realistic.

At this point, you can expect a clearance to cross, but the controller may want to see you on his radar before, so he’ll give you a transponder code.

“HB-XXX, sqawk 1234″

“Sqawking 1235, HB-XXX”. Here comes an important thing. At this moment, you’re not yet cleared to cross or enter any airspace. Wait until the next call.

“HB-XXX, cleared to cross via LSE, maintain 5′500 feet, report crossing completed”. To which you’ll answer the following: “Clear to cross via LSE, maintaining 5′500 feet, will report crossing completed, HB-XXX”.

If you can’t maintain the assigned altitude, or if the controller gives you a clearance you can’t cope with, say it as soon as possible. In some cases, the controller can amend your clearance, and give you a heading, or an altitude change, but here again, you can say “Unable” if you can’t comply.

Once you’re clear of the crossed airspace, don’t forget to report it, as simply as “HB-XXX, crossing completed”. If the controller assigned you a specific sqawk code, it will probably instruct you to sqawk VFR, otherwise the answer will be to leave frequency.

There’s not a lot more to say, except that under some circumstances, your request will be answered with a polite but firm “negative”. This is never pleasant, but as a well prepared pilot, you certainly have a plan. Ducking under airspace, or fly around, or turn back, but I’m sure you’ll not infringe that block of airspace.

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Category: Flying Tips
Tags: crossing flight planning phraseology TMA

“Affirm”
This shortened version of “affirmative” simply means “yes”. Yes was too short to be always cleary understood over radio, and “Affirmative” was too similar with “Negative”, so “Affirm” was created.

There are many reasons for which ATC can not always answer positively to pilot requests. Traffic, airspace restrictions, weather, worload, … but controllers do their best to anser with “Affirm” as often as possible. As pilot, I also do my best to answer ATC requests with “Affirm” as far as practical, to also help them, and to keep the system as smooth as possible.

“At your discretion”
This is kind of an extended version of “Affirm”. I can’t remember hearing it while flying VFR. I can imagine it for a pilot declaring an emergency, and being clear to land on “any runway at his discretion”.

“At your own discretion” is the perfect answer when and IFR pilot requests to deviate from his route to avoid adverse weather. We often request to deviate by XXX degrees to the left or to the right, to give the controller an idea. When controller answer such requests with “Turn is approved at your discretion”, it means that the pilot gets the freedom to turn as much as needed to circumnavigate the problem.

It is frequently accompanied by “Report when able to…”. Controllers know well that aircraft, and especially light ones, can not cope with any weather, or any problem on board. In case of emergency, controllers can also allocate a vertical slice of airspace to be used “at pilot discretion”.

“Direct to”
This one is definetly IFR oriented, but easy to understand for anybody. IFR routes are not always straight lines from A to B. There could be military zones, approach areas, or other restricted areas between A and B, but these zones are not always active.

By clearing a pilot to fly “Direct to XXX”, the controller shortens the route, saves fuel, and makes the pilot’s life easier, and this can also solve conflict problems over crowded intersectons. With modern navigation devices like GPS, but also inertial systems, it is possible to fly a direct to nearly every point on the globe.

A controller told me the story of a British Airways Boeing 747, shortly after inertial systems were introduced, who requested direct navigation to Cape Town… from Biggin-Hill VOR, in the London area. There was not a log of traffic, so he got it !

If you liked this post, have a look at the three things I don’t like to hear from ATC.

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Category: Pilots Talk
Tags: ATC IFR phraseology radio VFR

There are two frequencies that all pilots know by heart: 121.50 and 123.45. The first one is the emergency frequency that can be used at any time when safety of the flight is endangered. The second one… well… how to describe it… it’s piece of ambiguity.

ICAO Annex 10 states that “123.45 Mhz shall be designated for use as an Air-to-Air communications channel to enable aircraft engaged in flights over remote and oceanic areas, out of range of VHF ground stations, to exchange necessary operational information and to facilitate the resolution of operational problems“. As all ICAO documents, this is a recomnendation, which can be overruled by local laws.

Most of Europe is not continental nor remote, but several pilots do use it as a chat frequency. The UK NATS published an AIC (16/2003 Pink 53) to remind pilots that this frequency is not for general use by pilots, as it is officially allowed to some helicopters companies. Moreover using 123.45 in a UK FIR can result in interefence at other places (click here for more information).

Germany defined 122.80 as a “chat frequency”, and 123.45 is also used by Bangalore Tower (India). When googling it, I found many references mentioning this frequency being recognized as air-to-air frequency in the US, but no official confirmation. Finding the official chat frequency (if any) in the national AIPs or in the standardized Jeppesen manuals is not easy.

With such a complicated situation (referred to as a “mess” by some NATS collaborators), it’s not surprising that some urban legends exists about it in the flying community. The following dialog supposedly happened in Frankfurt:

“US-Airforce C-130: TWR tell 747 in front of us to call us on 123.45
TWR: XX777 would you mind calling C-130 on 123.45?
xx777: Sorry TWR, we do not talk on 123.45, we are professional pilots
US-Airforce C-130: OK, TWR tell those professional pilots they still have the gear pins in!”
(The pins are security locks put on ground to avoid unwanted retraction)

Now, I’d like to know what is your personal use of 123.45. No matter if you’re an airline pilot using it on the Atlantic, or a club-pilot using it to chat with friends, share your habits in comments.

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Category: Flying Tips
Tags: 123.45 frequency phraseology standards VHF