The short hops

[Tonic Please]

Regarding the regular hops I do from EGLL to LFPG. Just came over on BA316 on 28th, and it sparked a question that has been in my mind a while but never thought of as being worth while asking. Going back on the 8th in the evening, so I'm sure the same thing will happen then.

What is this thing?

Very simple question - The cruise is normally about FL240 on this route. The recent flight "appeared" to cruise for about 5 minutes (at the most!) before the noise lowered and we started descending. Being an aspiring aviator since the age of 2, and soon to start ATPL at 21ish, (aka somewhat informed with aviation), I began to wonder why they don't go to FL21 or FL20?

Would it not lower the workload, having an extra 10 mins of cruise, rather than getting as high as possible, then having a sip of tea before going back down?

Dan

[duece19]

FL20 is a bit low me thinks....

Im not familiar with the lower airways in that area, however jets prefer to get as high as possible, even if only for a short period of time. And even if they did choose to fly at FL200, the cruise portion would only be an odd couple of minuits longer anyway.

Im sure someone can give u a more decent explanation...

duece

[barit1]

Two quickly come to mind:

Traffic may be less at 240.

Burn less fuel by climbing to 240 even for a very short cruise, than by remaining 3k-4k lower for a longer cruise segment.

5 min. between TOC and TOD is just enough time for a reasonable engine cooldown from climb thrust - sounds like a good plan from that aspect.

[BOAC]

There are many reasons: the 'optimum' cruise level for fuel economy can be as high as Fl330. When DanAir used to deliver its outstanding business class service on the CDG route:{ cruise level was reduced to 210/220 and often speed to 250kts to help the c/crew with the dragging of the trolleys (uphill and downhill) and service time, with little noticeable fuel and no schedule time penalties.

Flying at 240 puts you in 'different' airspace as well which can affect routing and slot delays.

...................and you can still manage a tea (and a full hot meal:) )

[Tonic Please]

Thanks for the replies! Airspace didn't come to mind I must say. Not something a pilot should be saying :ugh:

While I'm here, on the 320/321 used on the route (in my experience), and knowing about ATC control etc, whats the general climb rates for the said route with a full plane on a normal day, provided ATC leave you alone!!?

Seems like we go up about 2500fpm and feel a significant nose drop to, as an absolute guess, 1500or so. Considering the pointy end want the plane up to FL24 asap, Id assume they'd maintain quite a steep climb.

Then again if not I guess they'd reduce power, as BOAC interestingly informed us about regarding the 250 knot cruise :uhoh:

[cdb]

Speaking of ATC...

There are also internal ATC agreements, and those between FIRs that limit levels for certain flights e.g. I believe flights from the London to the Amsterdam FIR are restricted to FL290 or below to help us "Spread the load" a bit.

[Doug E Style]

I know it's a slightly longer sector than you are asking about but I happened to have a spare nav log of a recent flight between London and Dublin and the fuel consumption figures it gives are:

FL300 - 2902kg
FL280 - 2959kg
FL260 - 2995kg
FL240 - 3012kg

On this flight the cruise portion of the flight was 117 miles and took 18 minutes.

Regards,

Doug