Stormy weather

[jan_olieslagers]

Looking at today's meteo, I realised few PPL's will take to the skies, not even to think of ULM's. Then I began to wonder: does wind of this kind keep airliners grounded? How strong would it need to be for that?

(For those unfamiliar with aviation weather reporting: 26G40KT stands for average wind speed 26 knots, gusting 40 knots. The cryptic coding dates from the teletype days, and of was of course never changed. There are decoders on the internet, but it's a nice show-off to read such code like a newspaper...)

METAR
METAR EBAW 210750Z 30026G40KT 9999 -SHRA SCT017 BKN045 08/04 Q1005 TEMPO 30025G35KT=
METAR EBBR 210750Z 29018G30KT 9999 FEW028 BKN033 09/04 Q1005 NOSIG=

TAF FC
TAF COR EBAW 210830Z 2109/2118 30020G33KT 9999 SCT020 BKN030 PROB30 TEMPO 2109/2113 SHRAGS=

TAF FT
TAF EBBR 210500Z 2106/2212 28020G35KT 9999 SCT020 BKN030 TEMPO 2203/2212 3500 SHRA SHRASN SCT008 BKN012TCU=

[Kapitein]

For the airliners I don't know.
But placing the boardingbridge against the aircraft isn't allowed anymore around 50 - 55KT.

[luchtzak]

Yesterday rides in the sky above Europe where very bumpy, it's challenging for cabin crew to serve drinks and ... landings are a challenge for pilots

No seriously: there are limits but much higher than 40 kts, we will have to wait for a reply by a real pilot!

[Depretair]

Yesterday rides in the sky above Europe where very bumpy, it's challenging for cabin crew to serve drinks

Confirmed, especially above Germany

[FlightSimCrew]

Just count the number of go-arounds today due to gusts.. but no problem here: SAFTEY FIRST.

Wind velocity limitation is based upon the maximum tailwind and/or crosswind components of the aircraft, which are different for each type.. In theory these have to be calculated before landing..

[jan_olieslagers]

Just count the number of go-arounds today due to gusts.. but no problem here: SAFTEY FIRST.

Hm. Safety's quite an issue, too.

Wind velocity limitation is based upon the maximum tailwind and/or crosswind components of the aircraft

Yes, sure. What are typical values for airliners?

[tolipanebas]

Looking at today's meteo, I realised few PPL's will take to the skies, not even to think of ULM's. Then I began to wonder: does wind of this kind keep airliners grounded? How strong would it need to be for that?

Although it is pretty windy today indeed, it is not that extreme either...
This kind of weather happens at least a few times a year, so it is almost routine to airline pilots, really.
Let's just say that it takes a bit more of our concentration and skills to take-off and land in it and it might be a good idea to take some extra fuel before you leave because a go-around is more likely, but apart from that, that's about it. Oh, and don't try an automatic landing, because that will not work for sure...
Today, you need real pilots.
I've done approaches in the UK myself with winds up to 55 to 60kts: check the weather in MAN, GLA, or BHX next time you hear of a storm in the UK and see what wind values can be reached overthere.

Now, I don't know if you realise this, but surprisingly enough, there is no such thing as a max wind to take off or land with! Think of it like this: in cruise, airliners regularly fly in jetstreams which can reach strengths of up to 150kts, and nobody even notices this!
What has to be taken into account for every landing and take-off is a TAILWIND and a CROSSWIND limitation, but provided you'd land or take-off facing into the wind (and thus reduce the tail- and/or crosswind component of the prevailing wind to below the manufacturer's demonstrated values), you could try to land with whatever wind there is. Now, if you'd try to do so with a headwind of let's say 100kts, you'd be creaping towards the runway with a ground speed of only a few tens of knots, but you could do it.

<For reference: typical tailwind values are around 10kts, and crosswind limitations around 35kts.>

As mentioned here before, the biggest problems actually starts once you're on the ground, because jetways have operating limitations too, as well as the aircraft door lock mechanisms, so you could very well end up in a situation where you'd have managed to land, but could not deboard your passengers (unless you'd have the plane parked behind a tall building to have quieter weather).

And then the question arises how you'd do an evacuation on the RWY in case of problems, since your doors are not guaranteed to stay open into such strong winds, at which point it is up to the pilot in command to decide whether or not to fly in and out of that windy airport, not because there is too much wind to land or take-off from it safely, but because there are other less obvious mechanical limitations to the plane which could potentially cause risks under certain situations...

I hope his gave some good insight in the matter?

[jan_olieslagers]

<For reference: typical tailwind values are around 10kts, and crosswind limitations around 35kts.>

This was the kind of info I was wondering. I suppose the max. crosswind component is higher for the heavier planes?

As mentioned here before, the biggest problems actually starts once you're on the ground,

This OTOH I had never realised. As a student ultralight pilot, getting the bird on the ground with not too much damage is the major achievement, all other concerns far less important. I now realise why airliners are so much harder!

[pressman]

typically B737-800 crosswind limit is 33kts with winglets , less if it is a wet runway .
I landed last year in 46g65 kts but straight down the runway , quite tricky approach but made a lot easier by the very low groundspeed .
We waited for the wind to drop before taking off again , actually the ramp closed as it was too dangerous . but for headwind normally it is a company limit or at the captains discretion . Personally I would not take off in 60 kts headwind probably 45-50 kts is my personal limit .

[jan_olieslagers]

Thank you sir, much appreciated!

[bits44]

How to determine what all the hieroglyphics mean:

http://www.met.tamu.edu/class/metar/metar-pg6.html

[tolipanebas]

<For reference: typical tailwind values are around 10kts, and crosswind limitations around 35kts.>

This was the kind of info I was wondering. I suppose the max. crosswind component is higher for the heavier planes?

Not automatically...

Cross wind limitations are often just DEMONSTRATED limits, meaning that during the certification process the manufacturer (or in fact its test pilots) have successfully demonstrated landings up to the specified cross winds, which will then be mentioned in the operating manual as 'max DEMONSTRATED cross wind limit'.

Now, if the pilots found the condition to be limiting, they will have made sure to have this included in the certification documents and as such the cross wind limitation becomes a HARD limit, meaning NOBODY may land with cross winds above this; if however they have found the cross wind conditions not to be limiting, then the word DEMONSTRATED is used and the operator may legally fly the plane in cross wind conditions above the demonstrated conditions.

Most airliners only have DEMONSTRATED cross wind limitations, meaning that the specified cross wind limit just depended on the weather conditions encountered during its certification and the manufacturer was not as lucky to find really extreme weather conditions. As I've said before: winds up to 35 to 40 kts are regularly found over wintertime and as such most airliners have similar DEMONSTRATED cross wind limitations, although some demonstrated cross wind limitation may actually be surprisingly low; a good exemple for this is the DC-8. Although pretty similar to the 707 in appearance and technology, it has a demonstrated cross wind limitation of less than 20kts, whereas the 707 had almost double that, not because the DC plane couldn't handle as much as it's Boeing competitor, but because the DC just didn't encounter more extreme conditions during its certification process...

Not surprisingly, the DC-8 was a plane which was operated above DEMONSTRATED cross wind limitations by many of its operators because of this reason. However, when the DEMONSTRATED cross wind limitation is such that it allows normal operations under most weather conditions (let's say the common standard 35kts or so), most operators will not allow their plane to be operated above these limits by their pilots, but some operators may still do so, especially those that operate in pretty extreme environments (polar regions for instance).

I had never realised. As a student ultralight pilot, getting the bird on the ground with not too much damage is the major achievement, all other concerns far less important. I now realise why airliners are so much harder!

Indeed, quite different from what you may have experienced yourself when flying la ight aircraft, but then you really can't compare an A320 of 60,000kg to a Cessna of only 600kg... were talking a factor "x100" here.

As a general rule when flying airliners, EVERYTHING is more complicated on the ground than airborne.
Flying really is the easy part thanks to all the technology we have but it is on the ground where everything is up to you and which make being an airline pilot a really though job: the many legal aspects which you have to take into account, the economic aspects the company asks you to deal with, local procedures which differ from place to place, the slot times putting you under time pressure, complicated handling procedures at some places, the always unexpected but always re-occuring last minute 'captain, we have a problem' item and even just finding your way around at night at big airports like CDG or LHR.... Flying is easy compared to this!

[jan_olieslagers]

Thanks again, very nice reading both for form and for content!