Singapore to London Track

[banana9999]

Evening

I flew back from Singapore on BA16 recently. The pilot told us that we would be going the "long way round" which had me worried for a moment as I didn't fancy a trip across the Pacific. However the route went over mid-India and Saudi Arabia before turning right into Turkey then over the bulkans into London.

Looking at the great circle route this is well out of the way.

Why is this? The flight was operated by a 777, do they have terrain clearance issues early in the flight?

Thanks

[Hartington]

Was the flight time more, or less, than you expected?

[PAXboy]

The winds of our earthly atmosphere have been known to move in mysterious ways ... The Jet Streams are in different places each day and sometimes each hour. In the same way that sailing ships would take a slightly longer route in order to have the winds 'in the right quarter' so with the ships of the air.

There is a calculation between having a tail wind on a longer route an a head wind on a shorter one.

[parabellum]

On any night there are at least a dozen departures to Europe from Singapore, several from Kuala Lumpa, Bangkok, etc. so it is possible there was a considerable delay on the shorter route but by re-planning the longer route it was possible to arrive on time into LHR, or just a little late instead of a lot.

Strong Westerly winds are highly probable too and possibly some closed or retricted airspace on the Northern route.

[SloppyJoe]

Will almost certainly be due to winds. Its 150+mph at the moment if you go further north. Average for the entire journey I would expect to be about 50kts headwind going further north. Going on a more southerly route you could expect this to drop to about 20. On a 14 hour flight this would equate to the plane having to fly through an extra 420nm of air to get to london. So about an extra hour.

The planners will look at this and also the cost of overflying, China, Russia etc which are more expensive than flying to the south. If it works out cheaper to go to the south they will. Sorry to tell you this but it will have nothing to do with getting you there on time, it will all be about which way is cheaper to go.

[parabellum]

Sorry to tell you this but it will have nothing to do with getting you there on time, it will all be about which way is cheaper to go.


Yes, times have changed! For a B744 an average wind component of -50 wouldn't be a problem anyway.

[TopBunk]

From December through late March (approx) the jet stream tends to drop south of the Himalayas, so you get a stronger westerly flow over North India.

During these months it is quite common for the first part of the SIN-LHR route to be as far south as you describe, as it ends up being a quicker albeit longer routing.

[arem]

Even more southerly was a route that took us from SIN over Sri Lanka, up to Oman , the north over western Iran, Turkey, Bulgaria and thence to LHR - all due to the strong Jetstream over India.

[wiggy]

FWIW..unless the Westerlies were really adverse I'd still expect the BA16, even on a 777, even in winter, to route via Pakistan and Afganistan ( and of course go any further North and there are terrain issues, even on the 744).

However as parabellum has alluded to there is the slot system ("BOBCAT") that regulates flow into Afgan airspace at peak times - I wonder if the OP's flight had a slot time problem and it was decided to route via Saudi to avoid a delay? I've certainly seen that tactic used ;) on that flight in the past.

[angels]

Even more southerly was a route that took us from SIN over Sri Lanka, up to Oman , the north over western Iran, Turkey, Bulgaria and thence to LHR - all due to the strong Jetstream over India.

For four years I used to fly frequently in between SIN/LHR and only did that route once. I reckon I did virtually every route variation in my time.

You could go to talk to the drivers in those days (which I used to do), and nearly every time the reason for the route choice was headwind related.

[peuce]

Wasn't QANTAS ( on the LON-SIN route) knocked back from entering Iraqi airspace around that time? Maybe other airlines were also skirting around it.

[crewmeal]

In any case why would the Iraqis refuse permission to overfly their airspace? I can understand the Iranian authorities being difficult, but seemingly not!! All very strange especially if they had planned this particular route.

[Yellow Pen]

What TopBunk says. I operated along that route recently and we also had an usual routing to keep us out of the very strong westerly winds. I've also flown SIN-LHR via the middle east and I recall the winds were the issue then too.