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-   -   Air France severe turbulence, mayday call (https://www.pprune.org/rumours-news/397440-air-france-severe-turbulence-mayday-call.html)

aa73 30th Nov 2009 17:07

Air France severe turbulence, mayday call
 
http://avherald.com/h?article=42380873&opt=0

captplaystation 30th Nov 2009 17:23

Sure someone is going to accuse them of being a bit jumpy, but if they possibly had to descend to a lower level NOW to maintain buffer margin, making a Mayday call was undoubtedly the best option to keep everyone flying anywhere near them in the loop.
Some new Pierre Cardin slips needed methinks :eek:

daikilo 30th Nov 2009 18:34

Facts
 
Not saying this did not happen, but plane was late departing. It seems actual arrival at CDG was a few minutes early compared to ETA predicted after take-off.

B777FD 30th Nov 2009 20:53

"An Air France Airbus A330-200, registration F-GZCK performing flight AF-445 from Rio de Janeiro Galeao,RJ (Brazil) to Paris Charles de Gaulle (France), was enroute at FL380 overhead the Atlantic on airway UN741 just before waypoint DEKON about 680nm northeast of Fortaleza,CE (Brazil) and 750nm southwest of Praia (Cape Verde), when the crew called Mayday on the international emergency frequency indicating, they encountered severe turbulence and were descending to a lower altitude. The airplane was seen enroute at FL280 overhead France and landed safely at Paris Charles de Gaulle 6:40 hours after the emergency call."

This implies the aircraft descended to FL280 for the remainder of the flight. :confused:

Dash-7 lover 30th Nov 2009 23:15

Looking at the weather graphics it looks eerily similar to previous events. Glad they made it back ok.

Remember mayday situation is one in which a vessel, aircraft, vehicle, or person is in grave and imminent danger and requires immediate assistance. I wonder how far they were from the nearest diversion point? Obviously the crew reassessed the situation and felt ok to continue to CDG. Probably pretty frightening all the same.

daikilo 30th Nov 2009 23:27

Facts
 
These words in quotes "..." are from Aviation Herald, which does not make them facts.

Again, I do not say it did not happen, but I would like to see more proof, pls.

golfyankeesierra 1st Dec 2009 06:57


Remember mayday situation is one in which a vessel, aircraft, vehicle, or person is in grave and imminent danger and requires immediate assistance.
Well, also remember that it is not easy to get a reclearance in oceanic airspace for situations of i.e. weather deviation or unability to maintain altitude.
When reclearance cannot immediatly be obtained, there are procedures in force that include use of pilot's annex 2 "emergency authority".
Captplaystation's explanation seems much more rational then the "panic in the cockpit" one.

no sig 1st Dec 2009 07:58

The following from the ICAO North Atlantic MNPS Manual, presume the same procedures apply on the southern oceanic routes,

Chapter 11: Special Procedures for In-Flight Contingencies

11.1 INTRODUCTION

11.1.1 The following procedures are intended for guidance only. Although all possible contingencies cannot be covered, they provide for such cases as:

• inability to maintain assigned level due to weather (for example severe turbulence);

• aircraft performance problems; or

• pressurisation failure.

11.1.2 They are applicable primarily when rapid descent, turn-back, or diversion to an alternate aerodrome is required. The pilot's judgement will determine the specific sequence of actions taken, having regard to the prevailing circumstances.

11.2 GENERAL PROCEDURES

11.2.1 If an aircraft is unable to continue its flight in accordance with its ATC clearance, a revised clearance should be obtained whenever possible, prior to initiating any action, using the radio telephony distress (MAYDAY) signal or urgency (PAN PAN) signal as appropriate.

Whippersnapper 1st Dec 2009 10:33

I have heard other aircraft make Mayday calls for exactly this reason, including a BA 747. I have also witnessed an ATR refuse to use it and accept holding in severe icing after being denied a request to descend. So, which is correct and which was plain stupid?

If you believe the aircraft or occupants are in jeopardy and need to change course or level contrary to ATC clearance, you use Mayday. Simple.

clear to land 1st Dec 2009 11:02

By definition 'severe turbulence' means that the aircraft is uncontrollable, therefore a Mayday call should be almost an automatic response: after all, the pilots no longer have contol!

barstow 2nd Dec 2009 04:26

Indeed, the non-aviation community does not understand the need for mayday in this context.

The unauthorized departure from assigned altitude is in fact a mayday, even if the aircraft is not spiralling into the sea. The mayday is issued because the immediate threat to life is any other aircraft already in the FL descended to, in the area, and the people on board the transmitting aircraft.

Completely normal, and completely logical.

No need for alarm here, folks...

RoyHudd 2nd Dec 2009 09:22

Just do it.
 
It is often not possible to get an immediate clearance from Dakar. (They hardly qualify as Air Traffic "CONTROL" in any event. Same applies to most African airspace, in truth).

Best to announce one's manoeuvres on 121.5 and 123.45, preceded by PAN, and just take avoiding action from CB's or severe turbulence. Radio plus the use of TCAS allows one to stay clear of dangerous weather, with far less risk to all than that provided by severe wx in the ITCZ.

Mr Optimistic 2nd Dec 2009 11:53

any substance to this ?
 
The Avherald site has this comment from a user

'The 4th incident during the last 2 weeks on this route I think...'

any substance to it ?

keltic 2nd Dec 2009 15:25

Can I ask something?. Do extreme weather occur throughout the whole year in the ITCZ?. In which season are storms more likely to happen?.

fhegner 2nd Dec 2009 16:12

hey Keltic

Wiki is your friend:

Intertropical Convergence Zone - Wikipedia, the free encyclopedia


"The ITCZ appears as a band of clouds, usually thunderstorms, that circle the globe near the equator. In the Northern Hemisphere, the trade winds move in a southwesterly direction, while in the Southern Hemisphere, they move northwesterly. The point at which the trade winds converge forces the air up into the atmosphere, forming the ITCZ.[2]

The tendency for thunderstorms in the tropics is to be short in their duration, but can produce intense rainfall. It is estimated that 40 percent of all tropical rainfall rates exceed 25 mm per hour (one inch per hour). Greatest rainfall typically occurs when the midday Sun is overhead. On the equator this occurs twice a year in March and September, and consequently there are two wet and two dry seasons. Further away from the equator, the two rainy seasons merge into one, with one wet season and one dry season. In the Northern Hemisphere, the wet season occurs from May to July, in the Southern Hemisphere from November to February.[2]

The location of the intertropical convergence zone varies over time. Over land, it moves back and forth across the equator following the sun's zenith point. Over the oceans, where the convergence zone is better defined, the seasonal cycle is more subtle, as the convection is constrained by the distribution of ocean temperatures.

Sometimes, a double ITCZ forms, with one located north and another south of the equator. When this occurs, a narrow ridge of high pressure forms between the two convergence zones, one of which is usually stronger than the other."


Microburst2002 2nd Dec 2009 16:51

Hi keltic
The ITCZ can be considered as the thermal ecuator.
Depending on the season and also monsoon effects, the ITCZ shifts north or south, but if you are in the ITCZ it doesn't matter what is the season. You are in it, and that's what matters.
If you have to fly from A to B and the ITCZ is in the middle, you have to cross it whether you like it or not. That's the problem. From South America to Europe, that is the case.

TopBunk 2nd Dec 2009 18:00

one of the problems is that the powers that be (in Frankfurt or London or wherever) decided that the ITCZ should be removed from the SigWx charts:mad:.

You now have to rely on knowledge, or look at the forecast winds on your Plog to see where they shift, or look at the CB forecasts to, at best, guess where the ITCZ may lie on a given day.

If anyone anywhere does not believe that the ITCZ is 'significant weather' they need flying through repeatedly it until they submit as a screaming crying wreck, the numpties.

keltic 2nd Dec 2009 18:36

Thanks for the replays. I have flown many times to Argentina and Brazil usually in end of march, beginning of April, and I have to admit that I have never found any significant problem. Even sometimes no many clouds in the area. Some turbulences, but nothing drammatical.

Sorry for the offtopic, but not being a pilot, this kind of dark area, was something completely new for me. Weather is such an amazing issue in aviation, which I think we have lots to learn about it.

Cloud1 2nd Dec 2009 19:06

I would not take too much notice of the Aviation Herald as it is a website full of crap - they even make a big deal over a birdstrike which is followed by a completely normal landing or a passenger requiring medical assistance on landing - they go way over the top and offer a whole new insight in to **** journalism.

cardhappyaf 3rd Dec 2009 12:10

i fly this route a lot using air france.

for me there is always turbulance at the point this happened. i dont think i have taken a flight where it hasnt happened.

i dont know what would be described as servere turbulance but certainly had some moments where i have sweated a few times....


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