I was wondering if someone is able to tell me a bit about turbulence from a pilot's perspective?
I'm always uncomfortable during turbulence, despite having flown literally 100 + times between Europe and Asia/Australasia. When the AirAsia A320 disappeared last year, it got me feeling more and more nervous as I have been transferred to Bangkok and will be doing weekly flights in Asia. I heard the pilots wanted to change altitude due to weather, their request was denied. (This fuels my nervousness)
I guess what I would like to know is how and what a pilot is able to do to minimise turbulence for passengers? Are there any strategies a passenger can use when flying in turbulence to assist in lessening discomfort?
I would appreciate any advice and information. Thank you very much.
Before flight, we use a number of different aviation forecasts to predict where there will be areas of turbulence. We then flightplan based on those forecasts, and might go lower than normal to avoid the turbulence. Normally at cruise altitude, turbulence is associated with convective thunderstorm activity or with jetstreams (strong winds at altitude). We get both text forecasts that give us the dimensions of expected turbulence, and then graphical versions of the same information. For the lower levels for departure and arrival we get similar forecasts. We can also predict ourselves when there may be turbulence on arrival - for example a strong wind that blows over a mountain range near to an airport.
So on arrival or departure we can amend our tracking laterally to avoid areas of expected turbulence and use the weather radar to avoid thunderstorms or associated convective cloud formations. Once in the cruise, ATC will pass information to us based on other pilot reports of turbulence, as well as updated weather forecasts that have come out since our departure. We can then pick a cruise level that is expected to be smooth - a lot of the time we climb to a level that we expect to be smooth and then see how it goes - you can always amend the cruise altitude once you 'have a look'. It is not uncommon to try a number of different levels before finding a smooth one, and of course it is a dynamic scenario and can change rapidly. Thunderstorm turbulence is generally easier to avoid than clear air turbulence associated with jetstreams, because you can see it (the thunderstorm, that is).
Once in turbulence, we fly a 'turbulence penetration speed' that is deemed by the manufacturer to be the best speed to fly in turbulence for the aircraft type. We will also turn on the seatbelts and tell you what is going on if we need to on the PA.
The ultimate responsibility for the safety of the aircraft rests with the pilot in command - if ATC deny your request and there is a safety imperative to that request, then you have the option to declare an emergency and manoeuvre as required.
I recall a conversation with ATC on a particular bad thunderstorm night out of Brisbane last year.
Pilot: 'Brisbane Centre, Airline123 require descent to Flight Level 320 due to severe turbulence.'
ATC: 'Airline123, Brisbane Centre, negative, opposite direction traffic below.'
Pilot: 'Centre, Pan Pan, Pan Pan, Pan Pan (declaration of an emergency), airline123, descending to Flight Level 320, leaving Flight Level 360 due turbulence,'
ATC: 'Airline123, Brisbane Centre, copy your Pan. Break break, Airline234 (the lower traffic), turn left heading 270, expedite, emergency traffic above descending (or words to that effect).'
That was on relatively clear VHF radio - it can get a lot crazier trying to organise similar clearance when out of VHF range on HF radio (which is much worse in terms of being able to hear ATC and with static on the line).
HBA also doesn't have an occupied control tower.
. This bit from the heritage register intrigues me:
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