Mountain Wave Question
We use best rate of climb for flying in up going wave, particularly when trying to gain height as I mentioned previously. Hitting the up flowing air and going to best rate. Mainly because of your ground speed. But also gives protection against local effects of airflow over the wing - causing a stall.
If you are flying into a 35 knot wind, best rate of a generic aircraft (no particular type) is 70kts IAS at 10,000' AMSL. Flying into your headwind at 70kts IAS (for arguments sake about 80kts TAS) with a 35kt wind is going to be around 45kts!!! Where as say Best Angle is 65kts IAS, (75kts TAS) which will give a Ground Speed of 40 kts. You aren't going to go anywhere very fast at either these speeds, and as I mentioned climbing at a 45kt groundspeed in downflowing air will mean you are experiencing this for longer, where as in downflowing air - lowering the nose, increase your Groundspeed, your rate of descent will increase, but you'll be out of the down quicker! Sometimes better than sitting there with a high nose attitude, high rate of descent, mountains/terrain approaching from underneath. You start running out of time and airspeed to do anything but hope you'll cross the saddle, or you'll smack into it.
By lowering the nose and gaining airspeed, you can see better the terrain you are approaching, you can judge the closure rates of height/speed/terrain and make a call whether you can cross the saddle easily, if not - then you have the airflow over the wings to make that Steep to Max Rate turn to get out of there.
I would never ever ever ever ever ever be in down flowing air in a C206 below 80kts - if I need to turn quickly below 80kts its almost a sure thing that at 10,000' it'll stall - and that turns a bad situation into a worse one!!!! But would not be more than a few knots over Va (121kts) - coz if you fall out of the wave and into rotor you don't want to be overstress the airframe either!
In wave if you're in downflowing air, there will be upflowing air within a mile upwind or downwind of where you are (it depends on mountain shape and form, windspeed and direction on the wavelengths, if its moist the lenticular clouds and rotor clouds will show when air is flowing up and down and areas of turbulence).
If you are flying into a 35 knot wind, best rate of a generic aircraft (no particular type) is 70kts IAS at 10,000' AMSL. Flying into your headwind at 70kts IAS (for arguments sake about 80kts TAS) with a 35kt wind is going to be around 45kts!!! Where as say Best Angle is 65kts IAS, (75kts TAS) which will give a Ground Speed of 40 kts. You aren't going to go anywhere very fast at either these speeds, and as I mentioned climbing at a 45kt groundspeed in downflowing air will mean you are experiencing this for longer, where as in downflowing air - lowering the nose, increase your Groundspeed, your rate of descent will increase, but you'll be out of the down quicker! Sometimes better than sitting there with a high nose attitude, high rate of descent, mountains/terrain approaching from underneath. You start running out of time and airspeed to do anything but hope you'll cross the saddle, or you'll smack into it.
By lowering the nose and gaining airspeed, you can see better the terrain you are approaching, you can judge the closure rates of height/speed/terrain and make a call whether you can cross the saddle easily, if not - then you have the airflow over the wings to make that Steep to Max Rate turn to get out of there.
I would never ever ever ever ever ever be in down flowing air in a C206 below 80kts - if I need to turn quickly below 80kts its almost a sure thing that at 10,000' it'll stall - and that turns a bad situation into a worse one!!!! But would not be more than a few knots over Va (121kts) - coz if you fall out of the wave and into rotor you don't want to be overstress the airframe either!
In wave if you're in downflowing air, there will be upflowing air within a mile upwind or downwind of where you are (it depends on mountain shape and form, windspeed and direction on the wavelengths, if its moist the lenticular clouds and rotor clouds will show when air is flowing up and down and areas of turbulence).
Mostly Harmless
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Best angle of climb will give you the best chance of avoiding obstacles, but there weren't any.
Best rate of climb will minimise your height loss in your situation & minimise any intereference with other airspace users
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I flew through a big thermal as I chopped the power on base on my second solo. Speed reducing nicely, attitude normal, two stages of flap out, a bit bouncy, glance at VSI & shows 2000 fpm climb - WHAT! Master overpowering urge to stuff the nose down but feeling a bit confused, recheck the nose is where it should be & AH agrees, speed still reducing to my target of 80. Decide it isn't me but I'm obviously high & not about to stall so reduced power and lowered the nose a bit. A few seconds later I'm descending normally. Probably old hat to more experienced pilots but it felt to me as if Emperor Ming the Merciless had taken control of my aircraft
Best rate of climb will minimise your height loss in your situation & minimise any intereference with other airspace users
.I flew through a big thermal as I chopped the power on base on my second solo. Speed reducing nicely, attitude normal, two stages of flap out, a bit bouncy, glance at VSI & shows 2000 fpm climb - WHAT! Master overpowering urge to stuff the nose down but feeling a bit confused, recheck the nose is where it should be & AH agrees, speed still reducing to my target of 80. Decide it isn't me but I'm obviously high & not about to stall so reduced power and lowered the nose a bit. A few seconds later I'm descending normally. Probably old hat to more experienced pilots but it felt to me as if Emperor Ming the Merciless had taken control of my aircraft
