Anyone know what the major airline policies/guidance are for deviation due to weather?
From my FCOM:
Monitor the weather at both long and short ranges in order to plan efficient
course changes. When avoiding storm activity stay upwind of the storm, if
possible. If thunderstorms exist over the landing airfield or landing reports
indicate severe turbulence, consider delaying landing or diverting.
Plan ahead to avoid large storms:
Avoid magenta and red radar returns and fringes by at least 20 nm.
Avoid single magenta areas of turbulence (not associated with heavy
precipitation) by at least 5 nm.
Avoid penetrating a cell or clear it’s top by less than 5000 ft, otherwise
severe turbulence may be encountered.
Do not overfly cells if the top of the cell is at or above 25000 ft to avoid
the possibility of encountering turbulence stronger than expected.
Avoid flying under a thunderstorm due to possible windshear, microbursts,
severe turbulence or hail.
If severe turbulence cannot be avoided, an increased buffet margin is
recommended. This can be achieved by descending up to 4,000 ft below
the FMS optimum altitude.
Adjust the tilt frequently in order to monitor storm development and to get
the best cell echo.
Curiously a LH flight and another AF flight the captains chose to try to pick a hole through the weather system.
I assume as they must still be alive, they did not "try to" they did pick a hole.
Is it a question of the captain filing a flight plan and it is never reviewed or questioned?
It does not happen like that. A large computer talks to another large computer and extracts all the weather, the winds, notices, navigation charges, fuel Price, and a hundred other items, and it produces an optimum route for the flight. The company file the flight plan. The controlling item is almost always cost. Having received all the paperwork for the flight I and the crew then review it all. If I think we need more fuel for the route, that is my decision. So if I see some nasty weather on my route that might cost me extra fuel, and I want to take extra fuel, I do. If I want another route, I phone the office up and ask for one. As Captain the buck stops with me.
For passenger/crew comfort and reduced wear I would say large deviations are a no brainer given the relatively low cost.
The 747-400 burns roughly 10,000kg of fuel an hour. It all adds up.
Safe and Commercial is the plan. Safety comes first always, but it needs to be commercial as well. After all the safest thing is just to stay in bed...