when to use Va airspeed?

[dominikos]

recently started to fly IFR and with experience of flying in some mild turbulence in and out of clouds I started to wonder whether I should drop the speed. When would you consider dropping airspeed to Va? In straight and leveled flight in turbulent air, would you drop to Va? How turbulent would it have to be?

Honestly, interested to see how folks approach it.

Thanks, Dominik

[Hank]

I've slowed to Va once, somewhere over Wyoming, off radar until I got close to Crazy Woman VOR. And I sometimes slow in descent when the bumps get too hard (they change from "bumps" to "thuds").

For cruising, I'm generally good if nothing is bouncing around the cabin and my wife isn't hitting the ceiling. 

[Ragsf15e]

If it’s bumpy, I’ll stay in the green arc but don’t slow all the way to Va.  mostly that’s applicable in the descent because I cruise high enough that I’m right around Va in cruise (indicated ~120mph around 10,500’).  If i slow in the descent it’s to make it more comfortable for passengers and to observe the green arc.

[philip_g]

I can’t say I’ve ever specifically slowed to va but the slower I go the less bumpy the bumps are

[David Lloyd]

If it is turbulent enough to throw your iPad or approach book from the seat to the ceiling, slow to Va.

[steingar]

How is it that you guys don't routinely encounter this in descent?

 

[Hank]

8 minutes ago, steingar said:

How is it that you guys don't routinely encounter this in descent?

 

At 500 fpm, my C descends nicely ~165 mph. My Yellow starts at 175 mph.

It's not always bumpy coming down. When it feels too rough (thud! thud! thud!), I'll pull some power, but I've never tried descending at Va = 132 mph at gross and lower at lower weights.

[steingar]

1 minute ago, Hank said:

At 500 fpm, my C descends nicely ~165 mph. My Yellow starts at 175 mph.

It's not always bumpy coming down. When it feels too rough (thud! thud! thud!), I'll pull some power, but I've never tried descending at Va = 132 mph at gross and lower at lower weights.

At 160 I'm solidly in the yellow and getting thumped around like crazy. Earlier C.  

[N201MKTurbo]

When the bumps get bad enough that you need Va, holding a particular airspeed becomes difficult. I usually throttle back until the average airspeed is somewhere around Va. 

[eman1200]

I found being around Va for the commercial maneuvers was very helpful.  otherwise, Va?  ppffffff......

[DXB]

I use Va in turbulence that is unpleasant enough to make me wish I hadn't gone flying that day. I have no idea if that's the best approach.  The rest of the time, I keep it under 175mph IAS in my '68C.   The bottom of the yellow arc in my plane is 150mph but changed to 175mph in '69 without a related structural change to justify the increase, so I am partial to the higher limit.

[A64Pilot]

When forced to penetrate thunderstorms, ask ATC for a block altitude and slow to Va, maintain Va and let the updrafts and downdrafts do as they will, just don’t get going fast to keep from climbing.

I’ve had to slow to Va a couple of times, once ferrying an aircraft down South and going through the ITCZ and once with the family on board going to San Salvador Bahamas. Of course if I had the option I would have diverted and or landed, but over water sometimes that’s not an option. Never intentionally penetrate a thruderstorm.

If a thunderstorm can kill Scott Crossfield, it can kill anyone. A thunderstorm can shred an airplane. even fighter jets have been shredded by them

https://www.aopa.org/news-and-media/all-news/2007/september/27/ntsb-releases-final-report-on-crossfield-crash

[jetdriven]

10 hours ago, A64Pilot said:

When forced to penetrate thunderstorms, ask ATC for a block altitude and slow to Va, maintain Va and let the updrafts and downdrafts do as they will, just don’t get going fast to keep from climbing.

I’ve had to slow to Va a couple of times, once ferrying an aircraft down South and going through the ITCZ and once with the family on board going to San Salvador Bahamas. Of course if I had the option I would have diverted and or landed, but over water sometimes that’s not an option. Never intentionally penetrate a thruderstorm.

If a thunderstorm can kill Scott Crossfield, it can kill anyone. A thunderstorm can shred an airplane. even fighter jets have been shredded by them

https://www.aopa.org/news-and-media/all-news/2007/september/27/ntsb-releases-final-report-on-crossfield-crash

In 13,,000 hours and nearly 30 years and I’ve never been forced to penetrate a thunderstorm.  

[N201MKTurbo]

3 hours ago, jetdriven said:

In 13,,000 hours and nearly 30 years and I’ve never been forced to penetrate a thunderstorm.  

You are lucky....

I’ve never willingly gone in or been forced, but twice, there I was. Wouldn’t recommend it.

i was talking to a WWII Mustang pilot once and asked him what they did about thunder storms during the war. He said they would bite down on a pencil to keep from biting their tongue off. He said you know you are in the middle of it when you see the colors. I have seen the colors. It’s like flying through a rainbow. All of a sudden the whole world is green or yellow. It would be beautiful if you didn’t think you were about to die.