"I doubt it would be very reliable (comparing the two pitot tubes)."I didn't mean it like that, Lee. I meant only the wind component coming directly onto the nose along the longitudinal axis of the aircraft. This is not so difficult to imagine... after all, that is basically what the PFD airspeed indicator is showing (minus the groundspeed) and the PFD airspeed is considered accurate enough to be used for takeoff). I can (almost) envisage a wind vector on the ND parallel to the track equal in magnitude to the PFD readout (minus the GroundSpeed) above 100Kts. Perhaps the gurus can help me out here (if I'm picturing this incorrectly).On the left hand side of the pic below is a diagram taken from my IRS notes showing how windspeed is computed. I've drawn a second diagram alongside showing how I think the ADIRU could interpret the data on the ground and display it as wind vector on the ND.http://members.ozemail.com.au/~b744er/WindVector.gif"It isn't like they have a wind vane up on top of the plane." Funny you should say that... I may have seen 747 Classics many, many years ago with so-called "Beta" Vanes (mounted on the underside of the nose, looking not unlike AOA sensors, but in the horizontal plane, like weather vanes), but I couldn't tell you what they were for (Gust Response Suppression?).Cheers.Ian.

Sure, I could see how you could easily get the headwind/tailwind component on the ground just from airspeed and groundspeed. Question is, do they do that?EDIT: Ian, I forgot to say, wow, that's a great picture!Lee Hetherington (KBED)

I guess due to the nature of the wind sensors on the plane (how they are constructed), they are not able to "see" sidewinds, and some values has to be calculated. For a takeoff, I would definately trust the windsocks at the airport plus meteo information, NOT what`s displayed in the ND. (At least not before rolling).

"For a takeoff, I would definately trust the windsocks at the airport plus meteo information, NOT what`s displayed in the ND. (At least not before rolling)."Not knowing much about piloting, I'd be interested to know what the average 737 pilot does with the meteo wind data.I previously understood that the headwind component (resolved along the runway centreline) was the thing the pilots were concerned about e.g. when computing takeoff speed adjustments (The crosswind component, of course, is not to be ignored if it is too strong for takeoff).I realise that the pilot should aready know what the wind is before takeoff, but I'm wondering if an accurate update (c/o of a wind vector on the ND) just before V1 might be of some use, especially if the headwind component suddenly became a huge tailwind (as it might do in a microburst)? This wind vector might be especially useful on those aircraft which have not been fitted with "Predictive Windshear" Weather Radar Systems.http://members.ozemail.com.au/~b744er/PWSTest1OJT.jpgCheers.Ian.

I don`t know much how the pilots do this either, I was just thinking the sensors are pointing forward, and will display winds having the runway direction properly, but further directional info is not acquired/computed before you start to roll. Would be nice to know what info the real-world pilots use. Niice display :)

The real FMC allows a runway wind entry on TAKE OFF Page 2 (which still is not modelled in PMDGs FMC). Then it computes the head and cross wind components (what the pilot also can do without the computer :) ). Under routine conditions, you don

I had to do a takeoff before answering :)On the INIT REF page, I noticed you can enter the wind and direction. I tried it, but guess it has no effect as it is greyed out, like the temperature? (LSK2R and LSK3R). When I started rolling, I got TAS and ground speed (from the wheel sensors?). At 4000ft AGL I finally got the arrow in the ND. Anyway, thanks for the info!Well, my beer sensor are telling me it`s time now, cheers :-beerchug

"Then it computes the head and cross wind components..."Thanks, Andreas... I didn't know that :-) (Just received the Bulfer 737NG FMC Users Guide in the mail, so I'll be sure to look it up. BTW, I'm getting a load of interesting answers to the question of why the vector can't be drawn on the ground (on various websites), but I'm still struggling with the concept. *:-* Cheers.Ian.