I agree with TOGABOY with the bay of bengal being one of the worst areas. I've never flown through that area without some very lumpy weather especially towards the western side near RGN or Nicobar islands. It is not unusual to see banks of thunderstorms hundreds of miles wide, their tops being well over FL400, other times there are just a few CBs but they are pretty impressive. Nevertheless lumps and bumps aplenty. Last year we had one particular episode for over 30 minutes, and that was after we had plotted our way around the worst of it. The cabin crew reported nearly every call light on for extra sick bags. The aircraft behind (QR I think) declared a medical emergency due to a woman going into prem labour. We spent the next 15 mins on RT relay just so he could divert to BKK.
I would concur that Perth can be very exciting when the wind is out of the north east and that the Bay of Bengal is also pretty bad at times but my worst experience was in mid Pacific a few years ago when rates of climb and descent varied from +1500fpm to -1500fpm and speed varied up to 30 kts. Lots of sick bags in use that day to!
Heading up the Bay of Bengal to CCU in the 70s in a VC10, I remember our Doppler telling us we were 150 miles X track desperately trying to steer around an ocean's worth of monstrous Cbs in the dark, all flashing and banging and shaking us to pieces. I remember looking at the control system hydraulic power control unit indicators and all 11 were showing amber lights- meaning starved of oil (as it was all levitated)! When a bad monsoon moves up into that area, it can be a place very not-to-be! There is always a westerly jetstream blowing along the N African coast which has its moments, but the worst I have always found is in the Indian Ocean- the monsoon there seems to be more powerful than other oceans, or maybe because it is my regular stamping ground.
Sometimes, at 01:30 in the morning clear sky, always there was Moderate Turbulence to Severe beginning at 5.000 agl. Northerly winds up to 60 KIAS, gradually decreasing as we loosed altitude near to Rwy 21.
I had my worst severe turbulence and associated wind shear in my life during an approach to Rwy 03 in a crystal clear night. We did a Go-Around, and passing 3.000 feet, it was smooth and nice again.
Next attempt we landed on Rwy 06, with serious turbulence on final below 3.000 feet.
I think they closed the Rwy that night after our landing.
I never ever found nice and smooth conditions flying through Bay of Bengal, because there are always huge CB’s, especially during Moonsoon season.
And since communications with Colombo and Calcutta remain on HF made our lives miserable every time we needed to deviate.
However, I have found that flying over China on winter, one can find some rough atmosphere sometimes.
In 30 years of flying, including the Bay of Bengal, clear air always the worst!
1. B707 500 miles off Newfoundland in severe turbulence, two galleys broke loose, pax and crew injured, then the yaw damper failed, rolling to 40 degrees of bank, had to make an emergency descent. How the aircraft stayed together I will never know.
2. B707 over North Africa in severe turbulence all the flight instruments failed...bar the standbys...no idea what mach we were doing...em desc into smoother air. Turns out from the flt recorder we descended at .94 mach! (seemed a bit noisy).
3. B737-200 just north of the Alps, heading north, NW jetstream of 150kts. In mod/sev turb aircraft, was descending at 1500fpm instead of climbing at 800fpm, to maintain speed. A following company a/c had 2 cc injured, one with a broken ankle, the other with a compressed vertibrae.
Weather or Ts turbulence is mostly finite, and avoidable, and you know when it will end! Clear air can be so unpredictable as to duration and severity. Turbulence on an approach is where the skill and judgement comes in...the fun bit!
One thing I have noticed- turbulence these days seems to be generally far less than back in the 70s/early 80s. In the VC10 then we were always rattling and banging our way around, but since I have been flying those same routes on the 747 (27 years), I get the impression that it's no big deal anymore......or have I answered my own question?
Paul Crickmore recounts on Pg 128 of Lockheed SR-71 - The Secret Missions Exposed a story of a SR-71 crew flying 974 in July '68 where they ran into storms in the Gulf of Tonkin with the tops of the clouds at 79,000ft! They overshot them at M=3.2 @ 80,000.
If you fly over the North Atlantic enough and hear the Americans, and latterly the Canadians too, clogging up 123.45 you'd think that the worst turbulence is with them. Funny thing but flying beside these chaps their turbulence reports are always worse than we Brits seem to experience. A frightened nation perhaps? Possibly not the wost turbulence but there always seems to be some activity at night routing overhead Charleston. At thirty odd thousand feet you can still be IMC and the radar just can't quite pick up some isolated CBs. Although not dangeous it can get extremely tedious after a couple of hours.