Airplanes and wind speed disruption

[Clariman]

DAK what wind speeds cause flights to be delayed or cancelled? We flew today and the BBC weather forecast said there would be wind speeds of 43mph at the airport when we departed. It was certainly very blustery and wind socks were horizontal, but there was no impact on flights and there was little more than a wobble on take off.

The plane took off into a headwind.

I ask because online info beforehand suggested that 40mph could cause disruption and we considered delaying our journey by 24 hours. I glad we didn't because flight was both comfortable and on schedule.

Thanks

[Breelander]

The plane took off into a headwind....

Crosswinds are the real problem, but apparently....

There is no headwind limitation for most commercial aircraft for take off, and therefore is no maximum overall limit for take off (or landing) ... However the reality is that there are wind limits for opening and closing the aircraft doors (around 45kts) and no pilots would attempt to taxi and depart in such conditions. The airport would have closed in such circumstances anyway!

https://www.flightdeckfriend.com/2019/0 ... nd-limits/

[Lootman]

Planes always take and off and and into the wind, for good reasons, so you should be more worried if you are not doing that. I once took off in the direction of the wind due to a special circumstance and I thought we were never to get off the ground.

Were you flying into Birmingham airport by any chance? The runway there is orthogonal to the prevailing winds and so you get a lot of cross-wind landings there. They are perfectly safe but require an entertaining crab-like positioning of the aircraft upon landing. There are lots of videos on Youtube showing them, although this short spectacular one is at Bristol:

https://www.youtube.com/watch?v=ZPn3MBNt7Rc

The other problem can be wind shear in the vicinity of the airport. That has caused a few accidents over the years although not recently.

More generally, any stormy conditions or poor visibility can cause ATC to space planes further apart, which leads to stacking and other delays.

[Clariman]

It was a flight from Glasgow and there was no wind disruption despite the winds. Funny you mention Birmingham because my most uncomfortable descent ever was a windy day at Birmingham airport. Rather than wait for a delayed connection to Scotland I hired a car and drove.

Clariman

[Dod101]

I have no idea what wind speed would ever be regarded as dangerous for landing or take off but often on long intercontinental trips an hour could be added caused by strong headwinds. Likewise, but flying in the opposite direction, a journey could be shortened by more or less the same amount of time. Cross winds on take off or landing are far more dangerous than a headwind.

Dod

[tjh290633]

Crosswinds are a problem on single runway airfields, like Gatwick. I recall being on the last flight into Manchester one day in the 1960s before it was closed by high wind. A colleague lost his hat as he left the aircraft that evening.

Light aircraft have limits on the wind speed in which they can operate, notably the Tiger Moth where the absence of brakes was a hazard when taxying downwind. In fact I had an accident in such conditions. I was unable to turn crosswind because of an aircraft on the approach on a grass airfield, and the propellor hit a 3x3 stake straight ahead, and broke. Had I had brakes I would have stopped so that I could have turned after the other aircraft had landed.

Another hazard with tailwheel aircraft is the tendency for a tail wind to lift the aircraft onto its nose, which is why they are often tethered when parked. I recall a comrade suffering this date when taxying downwind in a Chipmunk.

Modern jets can often be seen approaching crabwise in a crosswind, turning into alignment with the runway at the last moment. Feasible at a high landing speed, but impracticable with slower aircraft. Even so there are limits.

TJH

[gryffron]

ALL aircraft are limited by crosswinds at some point. Both sideways approach and crabwise landing are dangerous. Therefore, wind direction, and the WIDTH of the runway(s) is critical.

Very few modern large airports have multiple runways facing in different directions. Though such an arrangement is common on small and military airfields. Even those large airports which do have multiple runways they are usually parallel. All of Heathrow's runways have exactly the same alignment.

So the answer to the OP's question is that there is no single simple answer. There is some complex formula involving aircraft size, manoeuvrability, approach speed, wind speed and direction, runway width and length, which determines whether it is safe to land and take off.

Gryff

[Spet0789]

ALL aircraft are limited by crosswinds at some point. Both sideways approach and crabwise landing are dangerous. Therefore, wind direction, and the WIDTH of the runway(s) is critical.

Very few modern large airports have multiple runways facing in different directions. Though such an arrangement is common on small and military airfields. Even those large airports which do have multiple runways they are usually parallel. All of Heathrow's runways have exactly the same alignment.

So the answer to the OP's question is that there is no single simple answer. There is some complex formula involving aircraft size, manoeuvrability, approach speed, wind speed and direction, runway width and length, which determines whether it is safe to land and take off.

Gryff

For context, a 777 has a crosswind ‘limit’ (maximum demonstrated crosswind) of 40kts.

That could either mean a 40kt wind at right angles to the runway or (in theory) an 80kt wind 30 degrees off runway heading which would give a crosswind component of 40kts.

IIRC, these limits are lower when the runway is wet because getting everything straightened up properly on touchdown is harder in the wet. This is the only part of Gryff’s excellent post I’d disagree with - I don’t believe there are lots of other factors although obviously having a massively wide and long runway makes things easier.

By comparison, a light aircraft might have a 25kt equivalent number.

These numbers don’t typically mean that it’s a good idea even for a good pilot to land at these values. They mean that at least once during the certification of the aircraft, a test pilot pulled it off without bending the aircraft!

[tjh290633]

ALL aircraft are limited by crosswinds at some point. Both sideways approach and crabwise landing are dangerous. Therefore, wind direction, and the WIDTH of the runway(s) is critical.

Very few modern large airports have multiple runways facing in different directions. Though such an arrangement is common on small and military airfields. Even those large airports which do have multiple runways they are usually parallel. All of Heathrow's runways have exactly the same alignment.

So the answer to the OP's question is that there is no single simple answer. There is some complex formula involving aircraft size, manoeuvrability, approach speed, wind speed and direction, runway width and length, which determines whether it is safe to land and take off.

Gryff

You may recall that Heathrow was built with 6 runways in pairs at about 60° angles, in a Star of David configuration around the central area. Then this was reduced to 10/28 left and right, plus a single short runway using the original 04/22 runway to the east of the terminal area. That fell out of use some years ago, but it was only used for lighter aircraft.

The standard RAF layout had a 2000 yard runway on the prevailing wind direction, usually 05/23 or near, and two shorter runways at about 60° to each other. With grass airfields, the caravan just moved round to the correct spot for landing into the wind. The caravan dated from days without RT, when the occupant used red and green Verey lights plus Aldis Lamps to control movements on the airfield. Happy days.

TJH

[Lootman]

Very few modern large airports have multiple runways facing in different directions. Though such an arrangement is common on small and military airfields. Even those large airports which do have multiple runways they are usually parallel. All of Heathrow's runways have exactly the same alignment.

I can think of a few major airports that have non-parallel or intersecting runways. These obviously give more flexibility since they can minimise crosswind landings. From memory:

San Francisco (SFO) has two pairs of parallel runways that intersect in the middle. The longer pair are normally used for all landings and takeoffs for heavies. The shorter pair are used for narrowbody takeoffs.

Tokyo Haneda (HND) also has 4 runways with 2 parallel pairs although in that case the runways do not intersect - one of the pair are about 2/3 miles apart.

Bombay (BOM) has 2 non-parallel intersecting runways, but only one of them operates at a time, so it can be regarded as a (very busy) one-runway airport.

La Guardia (LGA) in New York has 2 runways that intersect close to the end of each.

Schiphol (AMS) has 6 runways, with 2 pairs of 3 being parallel, although 3 of the 4 longer ones are all aligned.

[csearle]

DAK what wind speeds cause flights to be delayed or cancelled?

As has been said each aircraft type will have a maximum safe crosswind component, which the pilot has to take into account. This is also applicable to taxiing.

As well as the steady wind there is also the size, of the gusts. This is communicated to the pilot along with the steady wind usually as the clearance to land is issued*. (I personally add half the size of the gusts to my landing speed, but this might make the landing impossible if the runway is too short.)

Planes always take and off and and into the wind, for good reasons, so you should be more worried if you are not doing that.

Whilst this is the general rule, "always" is I feel a tad too strong. Sometimes there are even more important reasons to take off and/or land with the wind.

* For example: Speedbird 867 Wind 280, 23 knots gusting 28 knots, cleared to land 26 Left.

[AleisterCrowley]

..
Very few modern large airports have multiple runways facing in different directions. T...
Gryff

You may recall that Heathrow was built with 6 runways in pairs at about 60° angles, in a Star of David configuration around the central area. Then this was reduced to 10/28 left and right
TJH

Not sure if they altered them slightly but Heathrow is currently 09/27 Left and Right. Perhaps they got a better compass...

[AsleepInYorkshire]

Totally on-topic

This was a definite brown trouser landing - noting this clip has over 14m views

https://www.youtube.com/watch?v=roS6oFjCDhc

Perhaps cross wind landings need excellent pilots as well

AiY

[dspp]

These numbers don’t typically mean that it’s a good idea even for a good pilot to land at these values. They mean that at least once during the certification of the aircraft, a test pilot pulled it off without bending the aircraft!

Actually the published limits for a type (whether crosswind or anything else) are ordinarily those that a test pilot considers could be achieved by a pilot without exceptional skill, i.e. an average line pilot.

(what constitutes an average line pilot is a whole 'nother bunfight)

A couple of randomish google links :
http://www.smartcockpit.com/docs/Crossw ... elines.pdf
https://www.easa.europa.eu/sites/defaul ... ection.pdf

regards, dspp

[tjh290633]

..
Very few modern large airports have multiple runways facing in different directions. T...
Gryff

You may recall that Heathrow was built with 6 runways in pairs at about 60° angles, in a Star of David configuration around the central area. Then this was reduced to 10/28 left and right
TJH

Not sure if they altered them slightly but Heathrow is currently 09/27 Left and Right. Perhaps they got a better compass...

I hadn't swung my compass recently.

TJH

[AsleepInYorkshire]

You may recall that Heathrow was built with 6 runways in pairs at about 60° angles, in a Star of David configuration around the central area. Then this was reduced to 10/28 left and right
TJH

Not sure if they altered them slightly but Heathrow is currently 09/27 Left and Right. Perhaps they got a better compass...

I hadn't swung my compass recently.

TJH

You would if you we're landing at Leeds Bradford Airport - you wouldn't swing it you'd - well - face it - head between your knees time My bad (again) Terrible side winds

AiY (Compass swinging and bar)

[Lootman]

Planes always take and off and and into the wind, for good reasons, so you should be more worried if you are not doing that.

Whilst this is the general rule, "always" is I feel a tad too strong. Sometimes there are even more important reasons to take off and/or land with the wind.

Yes, I went on to mention that "I once took off in the direction of the wind due to a special circumstance and I thought we were never to get off the ground."

The pilot explained this had to do with the high temperature (it was Austin, Texas in September) and the slope of the runway which was pronounced at the old airport there. All other flights were taking off and landing into the wind, but our flight had to go the other way. It was something to do with the payload - it was a full flight and we were going to San Jose, which is maybe a 4 hour flight. So we took off down the slope and with the wind.

Plane was a MD-80 which are fun because they feel like they are ascending very quickly - not sure if that is true or just a feeling.

Needless to say it took a long wait until there was a sufficient break in the traffic to pull that off.

[flyer61]

Interestingly the highest wind speed I have observed on an anemometer in the UK was at Machrihanish in the mid 80's. 72 knots! the Air Traffic tower was rocking. Thankfully my aircraft (well I was borrowing it off HM) was in the hangar.

60 knots from any direction will see flying stop for airliners. This is the limit for opening/closing the cabin/cargo doors.

The recent Hurricane that battered the Bahamas had the forecast as variable direction 80kts gusting 200kts

Cross winds per se are not that much of a problem. Unexpected tailwinds at takeoff and landing can catch out the unwary.

[tjh290633]

I was once in a Braniff DC8 which took off from La Paz in Bolivia, rather high in the Andes. The man in the seat next to me suggested I see how long the take-off run was - 2 minutes, I believe. You need a much higher ground speed at altitude to get the airspeed needed for take-off. It rattled and bounced and seemed endless, but we got off with runway to spare.

TJH

[scotia]

Cross winds per se are not that much of a problem..

Maybe not to a pilot, but they are a bit disconcerting for a prospective passenger at Stornoway, watching the Twin Otter arrive in a crab-wise fashion.