Modesto ILS problem

[Guest dwaohio]

I was flying to Modesto (KMOD) on a ILS 28R. I was on a perfect glide path and approx 500-600 alt the ILS needle droped rapidly and I found myself now High above the runway. It seems like the ILS ended about 1-2 miles before the runway and high. This is the standard setup and nothing was added to this airport or AFCAD. Please can someone help.Dave Albright

[Geofa 108]

I don't fly out there, but according to airnav.com Modesto does not have a ils 28l-it does have an ils 28r. The runways are fairly close and you reach 28r much sooner than 28l-could that explain it?http://mywebpages.comcast.net/geofa/pages/rxp-pilot.jpg

[Guest dwaohio]

Sorry I meant 28R.

[jvile 1]

The ILS needle did not go low because something is wrong with the GS transmitter owned by the runway properties in FSX.What happened was the plane went high (monitor FPM descent rates)because you flew through a strong thermal on approach to the runway.FSX models thermals and turbulance into the world and you can view where they are if you have the SDK's. Real world pilots rely on other pilots and Tower to tell them of possible thermals and turbulance at airports that don't have the ability to monitor. In FSX you must always be prepared for it.Some thermals are very strong and cross the approach path of a runway. That in turn forces the plane upward without warning and you the pilot must know how to deal with these weather wind issues on approach. Also the thermals may be having an effect on your plane but not on the windsock or what ATC sees as the correct wind settings.If you don't like the thermal effects in FSX then turn them off by placing a checkmark in the proper box under optionssettingsdisplayweather menu.

[Mace 1,902]

Agreed; you probably hit a thermal. I turned them off after I had about 3 or 4 nice approaches suddenly go sour because of it.The problem is, if you turn it off, you lose the little turbulence ("living airmass") effects that are nice in FSX. I guess I could turn it off on approach and leave it on the rest of the time.RhettAMD 3700+ (@2310 mhz), eVGA 7800GT 256 (Guru3D 93.71), ASUS A8N-E, PC Power 510 SLI, 2 GB Corsair XMS 2.5-3-3-8 (1T), WD 250 gig 7200 rpm SATA2, CoolerMaster Praetorian case

[Guest jonasbeaver]

flying both small and medium aircraft I have found there really are thermals so strong on final you either cut power and slip to land or go-around due to thermals... especially in hot places (florida and texas where I fly for real)now that said with a large aircraft that I am sure "ain't" quite the casecheers!

[ccaughie 0]

That's interesting to know -- I've had many landings messed up by the thermal behaviour and have often wondered if the same thing happens in real life.One time I did cut power and used full flap to try (with limited success) to keep my speed down. I didn't think of sideslipping, I'll try that next time. I managed to get down to the runway, but only by maintaining a ridiculous nose-down attitude and landing nosewheel first. I think I was flying the Mooney Bravo, possibly the Cessna.It seemed that the updraft was as strong as ever even a few feet above the runway. Surely real thermals don't do that??Or is it possible that I'd built up too much speed and it was the flaps that were generating the lift by the time I reached the runway?

[Guest emkramer]

nevermind.

[Mace 1,902]

I kind of think the thermal effect is overdone--doesn't seem right that a big plane like a DC-6 can "hang" in mid-air, nose pointed way down, gear down, notch or two of flaps, and yet be CLIMBING at 800 fpm.RhettAMD 3700+ (@2310 mhz), eVGA 7800GT 256 (Guru3D 93.71), ASUS A8N-E, PC Power 510 SLI, 2 GB Corsair XMS 2.5-3-3-8 (1T), WD 250 gig 7200 rpm SATA2, CoolerMaster Praetorian case

[eskimo 0]

I have tried many times trying to land at MOD. The thermal just lift up the airplane when I am getting close to the runway.Thanks for the tip to turn off the weather simulation but any suggestion how to land the airplane when thermal is present?I got really frustrated...

[Guest bstolle]

I have tried many times trying to land at MOD. The thermal just lift up the airplane when I am getting close to the runway.Thanks for the tip to turn off the weather simulation but any suggestion how to land the airplane when thermal is present?I got really frustrated...

IRL this can seriously de-stabilize the approach and might even require a go aroundIf the plane starts climbing above the glideslope you might even have to reduce the power to idle to stay on the glideslope.The problem occurs afterwards where you enter the area of the surrounding downdraft.If you are are still at idle when entering the downdraft and that happens very close to the runway e.g. at a too low altitude, you might not be able to prevent a 'landing' short of the runway because full power might be available too late.You have to decide rather early to execute a go around because you KNOW that after the updraft the downdraft will hit you.IRL you could try another approach as the thermal might have shifted during the next try but in FSX they are stationary, so it's for sure better to land from the opposite side with e.g. 10kts tailwind.BTW, KBLI also 'features' such a thermal (approaching from the shore side) but it's at an altitude where it's barely possible to re establich a normal glide slope. I like this very much because it keeps you alert and it's good training!