So it will give the stewards more time to sell goods from their trolleys more like.

This is very misguided and in accurate. The flight speed is dictated by the route and other air traffic or indeed with the case of Thomson the aircraft type being changed. It is not up to anyone but atc to say what speed they travel at.

It might be inaccurate but you have to admit the idea of flying a few mph slower is quite amusing - I love driving down the motorway trying to improve my mph on a long trip
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bluemoon1,

I would ask what pilot qualifications the person who told you that has Aircraft have economical cruising speeds, ie the most fuel efficient speed the aircraft can fly at. I will quote them if you wish. This is actually at a faster speed, not a slower speed. For example, on a Boeing 767, the economical cruising speed is 850kmh (460kt) with the maximum cruising speed of 900kmh (486kt). As you can see, the economical cruising speed is close to the maximum. Also, when flying at altitude, an aircraft will stall unless it's at a high speed with some tight margins. This is due to the air being thin up there and often referred to as cofin corner. It's often not possible to slow the aircraft without reducing altitude which will actually increase fuel burn. As BEfreeTODAY also mentions, ATC will assign speeds so it's not always up to the crew.

It's the addition of winglets on some aircraft that has lead to reduced fuel burn, as well as weight saving measures and the use of various continuous descent patterns. A reduction in aircraft speeds is far from the truth and only a part of it. Any measure to reduce fuel burn has to be good though.

Darren

I think that this has all the characteristics of an urban myth - I first came across it some years ago and in having a quick scout around on the Net it looks as if there was a veritable slew of stories about a whole host of different airlines doing this starting in APRIL 2008 especially

But like many an April Fool - especially the good ones which always have an air of plausabilty about them on first reading - once they start circulating they lose the orginal dateline and take on a life of their own.

PS Have a look out for the one which said that the airlines liked red eye flights because they were more economical on fuel too - and the debates that took place on various forums about why this might be

SM

The cruising speed is determined by the operator and is included on the flight plan. However, this can be modified by ATC to ensure spacing between aircraft (usually in the climb, the approach and always when crossing the North Atlantic) . Cruising speeds have reduced over the years as a fuel saving measure and aircraft that used to cruise at Mach 0.83 are now often using Mach 0.80 for the cruise.

aircraft that used to cruise at Mach 0.83 are now often using Mach 0.80 for the cruise.

I'm struggling to make sense of these figures. Dredging up my long ago Physics A level knowledge, I understood Mach to be a ratio, ie a comparative measure rather than a fixed one because the speed of sound isn't a constant, it varies depending on the density of the air which is affected by both temperature, humidity and altitude. At ground level at 15C Mach 1 is roughly equivalent to 1225km/hr and this would crusing speeds of 1016 km/hr and 980 km/hr respectively (or put another way, a difference of approx 22 miles per hour) - both of which are above the maximum crusing speed that Darren gave for a Boeing 767. Are there many commercial passenger aircraft capable of flying at around 1000km/hr?

But what I can't remember is whether sound travels faster or slower at the sort of altitudes and low temperatures that commercial aircraft fly at. I know that efficiency comparisons between aircraft and cars aren't really meaningful (and this is where I'm reaching the limits of my maths!) but a difference of .03 % pts to your driving speed would be barely noticeable so assuming the quoted figures correct, just how significant are they anyway?

SM

Speed of sound reduces with altitude. It is a function of altitude and temperature. To give a rough example the speed of sound at sea level is about 660kts and at a cruising level of 35,000ft it is about 575 kts. Thus mach 0.8 gives an airspeed of 460kts.

The difference between mach 0.83 and mach 0.80 is round about 20kts. It doesn't make a lot of difference on a short hop but it will add round about 25minutes to a flight to Cancun or Las Vegas. In spite of the extra flight time the aircraft will use less fuel.

What the crew told you was true, whilst they may not be pilots they spend a lot more time talking to Thomson airways pilots than others. In fact yesterday an Easyjet aircraft was scheduled to take off 20mins prior to us and land an hour before us at destination. If Thomson airways are not
Flying slower easyjet have bought Concorde as it's very hard to make up 40 mins on one short haul sector.

Thomson airways has reduced their speeds over the last few years and it is noticeable now. Some pilots keep to the most efficient speeds but the majority tow the company line, which are slower. Every route is now longer than when I started flying and as far as I can tell the UK hasn't moved.

I've noticed in the airline fact sheets that newer planes tend to have lower maximum speeds than the ones they replace. It's not a simple equation. If you fly fast you use more fuel, it's exactly the same as a car (although take off uses a disproportionate amount which isn't normally a problem car drivers have!). But if you go too slow you might lose the chance to get in one more revenue earning flight out of that day's leasing costs/ crew hours.

A few years ago I came back from Milan on a very delayed Alitalia flight where the crew were overnighting in Manchester and were due back on a breakfast flight. When we finally took off there was a risk of them not having the required break, not only did they get us back much faster than it said in the timetable (that's common, scheduled flight timetables are usually padded) but they cut about 20 minutes off the outward flight time. Regular passengers couldn't believe how fast the plane could go (I couldn't believe Alitalia had regular passengers!).

Last edited by Kiltman HT Mod on August 31st, 2011, 8:45 am, edited 1 time in total. with the reason given:
Unauthorised Signature Removed

I have just spotted the above edit to my post, - can I ask what the difference is between putting my name into a post manually each time and the fact that it is there automatically as I use Tapatalk for most of my forum post except when at work.

Also out of courtesy I think a PM or whatever the Holidaytruths equivalent is would have been nice.

can I ask what the difference is between putting my name into a post manually each time and the fact that it is there automatically as I use Tapatalk for most of my forum post except when at work

Hi Feebee

There isn't a problem with you adding your name, however it was NOT your name that was removed, a weblink signature to Google Maps showing your location was the signature removed from your post and this was done for your personal security.

Graham

Sorry Graham it is those darn Geotags Tapatalk has added :(. I keep trying to disable them and I must have missed this one.

Apologies.

Wow, You guys have impressed me. but you lost me too.
I can never remember it taking 3 hours to get to Spain, so I reckon they all must be flying slower.