Max Cross wind
Chally604 re #17. Rather than ask if the approach and landing will be legal – can I do this, ask ‘should I be doing this’, is it sensible.
Whilst the advice above varies – limits are limits, the use of any interpretive information must be your decision. Why trust the outcome of your landing to someone else’s opinion. However … IMHO (where on occasion I have determined a demonstrated crosswind in test flights), the published value should include the gust.
There is plenty of evidence from accidents and studies (decurion #15), which indicate that pilots’ risk assessments are weak, either due to lack of information about the conditions, poor knowledge about the factors in the conditions, or the application of knowledge (choice of action).
Perhaps you should ask ‘when did I last land in the max steady crosswind, if ever – what’s my currency’, what’s different – runway width, surface texture, speed, tyres, IS THE SURFACE WET (even damp).
Don’t forget that risk is not only associated with being able to land a crosswind, its also staying on the runway during roll out. IIRC there is a report that many excursions ‘side-exit’ incidents occur at relatively low speed.
A legal view may only affect biscuits with tea at the interview, alternatively a formal investigation.
A sound judgement is always be defensible (as per checkerboard #18)– you did you best in the circumstances – the culminating aspect of airmanship.
Whilst the advice above varies – limits are limits, the use of any interpretive information must be your decision. Why trust the outcome of your landing to someone else’s opinion. However … IMHO (where on occasion I have determined a demonstrated crosswind in test flights), the published value should include the gust.
There is plenty of evidence from accidents and studies (decurion #15), which indicate that pilots’ risk assessments are weak, either due to lack of information about the conditions, poor knowledge about the factors in the conditions, or the application of knowledge (choice of action).
Perhaps you should ask ‘when did I last land in the max steady crosswind, if ever – what’s my currency’, what’s different – runway width, surface texture, speed, tyres, IS THE SURFACE WET (even damp).
Don’t forget that risk is not only associated with being able to land a crosswind, its also staying on the runway during roll out. IIRC there is a report that many excursions ‘side-exit’ incidents occur at relatively low speed.
A legal view may only affect biscuits with tea at the interview, alternatively a formal investigation.
A sound judgement is always be defensible (as per checkerboard #18)– you did you best in the circumstances – the culminating aspect of airmanship.
There is plenty of evidence from accidents and studies (decurion #15), which indicate that pilots’ risk assessments are weak, either due to lack of information about the conditions, poor knowledge about the factors in the conditions, or the application of knowledge (choice of action).
"The limit is 35 knots"
Ah, what if the speed in given in mps?
"THE LIMIT IS 35 KNOTS"
"Ah, what if the wind was only exceeding 35 knots for a little bit?"
"The limit is 35 knots"
"AH .. What if I landed over 35 knots, but time averaged the wind over the last day or so, until I could come up with an average below the limit?"
"THE LIMIT IS 35 KNOTS, what part of this is difficult to understand?"
Ah, what if the speed in given in mps?
"THE LIMIT IS 35 KNOTS"
"Ah, what if the wind was only exceeding 35 knots for a little bit?"
"The limit is 35 knots"
"AH .. What if I landed over 35 knots, but time averaged the wind over the last day or so, until I could come up with an average below the limit?"
"THE LIMIT IS 35 KNOTS, what part of this is difficult to understand?"
If I give you an airspeed limitation, wouldn't you expect me to tell you if that's IAS, CAS, EAS, TAS or Mach number?
If I give you a manoeuvring speed, wouldn't you expect me to tell you what you are and are not permitted to do with the controls above that speed?
If I give you a wind limit, wouldn't you expect me to tell you what I meant?
So put another way:
How did you measure the "38 knot gust" during which you claim I left the runway? Was it at tower height half a mile away, or at the surface? Did you read it off the INS?
Here's what the paper decurion cites has to say:
Depending on the way the data are analyzed crosswind derived from the INS system includes or excludes wind gusts. At least one large aircraft manufacturer uses the INS data to derive a crosswind by plotting the crosswind component as function of time. The crosswind at the time the aircraft is 10 meters above the ground is then read off the plot. Engineering judgment is used in fairing the data. Another manufacturer has a different approach in determining the crosswind value during flight tests. During the flight tests the pilots of this aircraft manufacture requested the tower wind when the aircraft was close to a height of 10 meters from the ground. The mean wind given was then used to compute the crosswind during the crosswind certification flights. If this last aircraft manufacturer had used the approach of fairing INS data as mentioned before, the demonstrated crosswind capability for one of their aircraft would have been at least 10 knots higher than presently mentioned in the AFM of this aircraft.
If I give you a manoeuvring speed, wouldn't you expect me to tell you what you are and are not permitted to do with the controls above that speed?
If I give you a wind limit, wouldn't you expect me to tell you what I meant?
So put another way:
Real world - it only matters if you crash, and are attempting to explain to a non-pilot, frequent passenger judge, how you left the runway in a 38 knot gust you were warned about and knew was:
possible, and
was greater than the certified aircraft limit.
possible, and
was greater than the certified aircraft limit.
Here's what the paper decurion cites has to say:
Depending on the way the data are analyzed crosswind derived from the INS system includes or excludes wind gusts. At least one large aircraft manufacturer uses the INS data to derive a crosswind by plotting the crosswind component as function of time. The crosswind at the time the aircraft is 10 meters above the ground is then read off the plot. Engineering judgment is used in fairing the data. Another manufacturer has a different approach in determining the crosswind value during flight tests. During the flight tests the pilots of this aircraft manufacture requested the tower wind when the aircraft was close to a height of 10 meters from the ground. The mean wind given was then used to compute the crosswind during the crosswind certification flights. If this last aircraft manufacturer had used the approach of fairing INS data as mentioned before, the demonstrated crosswind capability for one of their aircraft would have been at least 10 knots higher than presently mentioned in the AFM of this aircraft.
I wouldn't be measuring the gust! I am saying that IF you ran off the side of the runway, after a tower report (from tower measured wind) of gusts over the aircraft limit ...
... well I would imagine that would be very hard to explain to a judge.
Now you and I both know all of the caveats on wind reports and demonstrated crosswind limits - but convincing a judge and/or jury of that will sound a little .. um ... like a contrived excuse.
Not to say I'm not happy to land over demonstrated limits - I have before and I guess will again. (My current company has an ops manual hard limit though - and it's their play set.)
I am saying that IF you ran off the side of the runway, after a tower report (from tower measured wind) of gusts over the aircraft limit ...... well I would imagine that would be very hard to explain to a judge.
Now you and I both know all of the caveats on wind reports and demonstrated crosswind limits - but convincing a judge and/or jury of that will sound a little .. um ... like a contrived excuse.
Not to say I'm not happy to land over demonstrated limits - I have before and I guess will again. (My current company has an ops manual hard limit though - and it's their play set.)
