As we get closer to Summer, I’m reviewing my W/B as the DA will get pretty crazy around the Western States. Using Google Sheets below is a nice little spreadsheet that helps me calculate different loading to estimate OGE hover, range, fuel burned, etc. What’s calculating your DA tonight before the dawn?

Note: using MyE6B app also on iPAD

We kill almost a person a year here due to DA. Our density altitude hovers around 10,000' in Flagstaff for most of the summer. So the airport has electronic signs at the approach end and in the runup area. We get people transiting the area not really paying attention to things like leaning before takeoff and how it may affect your load carrying ability. Then suddenly they get to get a first hand experience with the trees/ditch discussion we had here a week or so back. Never got to ask any of them how it went, like Elvis, they are dead.

It seems every device I have gives me density altitude from the G1000 to the Apple watch. The place that DA eliminates for me in the summer is Lake Powell. If I have a load of fuel, my water run can approach infinite, since its DA also gets near to 10,000' at times. Not a bad thing you brought this up, since some folks may wander down to northern AZ, southern Utah and northern New Mexico. It gets warm, but not hot here. Which is deceptive, since the Colorado Plateau is makes everything above 5,000' AGL to start. People just do not think about it, it really affects how your wing works, engine performs and what your prop does for you. Even your flight controls are affected, until you try it out, you can be amazed by how they just don't do much. I took my Soloy 207 up to 23,000' to do some fuel burn testing. I could wack the yoke lock to lock on roll and it would barely move. It flew ok, but just don't think things will work like you expected.

The guys that really get affected here are in Bonanzas and Piper Cherokee 140's. Bonanzas can use all the runway here and climb at a very leisurely pace if they are heavy. The Pipers get stuck here, having to wait until early morning to wheeze into the air. Both tend to dominate our statistics as well. Aside from the DA, we tend to be windy (no not my writing!), couple that with the DA and your less effective performance package. Our airport tends to have to buy runway lights in 6 packs due to people not staying on the concrete part. Uprated engines are popular here with the locals. There is the occasional dummy who buys a plane only to realize its service ceiling is the DA of the airport. Looks cool in the hanger.

I got my CFI while at NAU. The FBO used the new AA1-As that were later Grumman. That's where I got this "airplanes won't necessarily climb" tick, which has worked well for me ever since. So a flatlander gets off but can't climb. Level in low ground effect and down drainage egress helps a lot. As does default leaning.

Check ride with FAA back then was at Scottsdale. Students could fly sanctioned pattern down there.

contactflying wrote:I got my CFI while at NAU. The FBO used the new AA1-As that were later Grumman. That's where I got this "airplanes won't necessarily climb" tick, which has worked well for me ever since. So a flatlander gets off but can't climb. Level in low ground effect and down drainage egress helps a lot. As does default leaning.

Check ride with FAA back then was at Scottsdale. Students could fly sanctioned pattern down there.

I soloed at Scottsdale Municipal Airport, AZ back in High School. There was a boarding school called Judson in Paradise Valley back then. I convinced the headmaster to allow me to take a cab to the airport in the afternoon after classes. We also flew radio controlled at the school. A new Cessna C172 was $14,000.00, VFR.

dogpilot wrote:...The guys that really get affected here are in Bonanzas and Piper Cherokee 140's. Bonanzas can use all the runway here and climb at a very leisurely pace if they are heavy. The Pipers get stuck here,...

The Piper Cherokee 140 is dangerously under powered. A CFI was killed and the student injured on the Island of Lanai during a night training flight. DA never is above 3K and generally strong headwinds. But...

Lanai has a notorious downdraft coming down from the rising terrain during strong trade winds. The Piper Cherokee 140 simply couldn’t climb and crashed full power into a pineapple field.

The student said the aircraft wasn’t climbing as they turned crosswind. Conclusion was inability to climb during strong downdrafts. Engine was making full power. Pilot and student were “heavy” people.

Note: an A&P and I had performed maintenance the night before and I was horrified to read about the crash in the news. The FAA reviewed the logs etc and concluded the aircraft was airworthy.

Hannagan Meadows heliport near Alpine Arizona is on the Mogollon Rim at 9100 feet. I've hitched a ride on a Bell 407 out of there on a hot day. It seemed to have quite adequate power. The kids on the helitack crew called that place a "Suck hole".

tcj wrote:Hannagan Meadows heliport near Alpine Arizona is on the Mogollon Rim at 9100 feet. I've hitched a ride on a Bell 407 out of there on a hot day. It seemed to have quite adequate power. The kids on the helitack crew called that place a "Suck hole".

Turbine helicopters have considerable power vs. weight in contrast to my reciprocating engine.

Example (note for entertainment only, please consult POH):

1) R66 empty is 1280 lbs vs an R44 Cadet 1500 lbs empty (turbine is 220 lbs less for a five seat)

2) R66 OGE hover at 2700 lbs GW is over 10,000’ DA

3) R44 Cadet OGE hover at 2200 lbs GW is 5100’ DA

Amazing difference! However, the R66 is 3x cost (approximately). The R44 Cadet requires me to off load during high DA.

And like the fixed wing, the big round wing will accelerate in low ground effect where climbing would cause settling with power.

contactflying wrote:And like the fixed wing, the big round wing will accelerate in low ground effect where climbing would cause settling with power.

However, many places such as a confined area requires a vertical in and vertical out path. Which in itself requirers a lot off power and is inherently dangerous at any DA. But, becomes more dangerous as power is limited. Ground effect may lure you into a flight regime that can destroy the ship. Power checks out of ground effect are paramount (and could of saved a lot of lives if implemented properly).

Are you familiar with the Army's simple TOL Card for estimating power needed at a higher DA from takeoff? We had good luck with them at Mountain Flying Course at Ft. Carson. It is based on power to hover 3' at takeoff elevation. Up on Pikes Peak at 14,000 we zero airspeed about a 3/8 mile out and set the calibrated torque
with collective. From there to hover in the LZ, the collective is not moved. To go down on the glide angle we manipulate the cyclic to get a little settling with power. To go up on the glide angle we move the collective forward a bit. It is amazing to not have to touch the collective while settling into a 3' hover.

contactflying wrote:Are you familiar with the Army's simple TOL Card for estimating power needed at a higher DA from takeoff? We had good luck with them at Mountain Flying Course at Ft. Carson. It is based on power to hover 3' at takeoff elevation. Up on Pikes Peak at 14,000 we zero airspeed about a 3/8 mile out and set the calibrated torque
with collective. From there to hover in the LZ, the collective is not moved. To go down on the glide angle we manipulate the cyclic to get a little settling with power. To go up on the glide angle we move the collective forward a bit. It is amazing to not have to touch the collective while settling into a 3' hover.

No. And I couldn’t find any reference to “TOL Card” in the plethoras of training material available. Is there any reference you could forward me? What year did you complete the course? Sounds over simplified and dangerous from your description. I can not believe the military would instruct that. Please provide support documentation?

“... To go down on the glide angle we manipulate the cyclic to get a little settling with power..”

There is absolutely no reason to have any settling with power or vortex ring state whatsoever.. The sink rate needs to be slowed or TAS increased.

1976. I was in the 717th Medical Detachment to the NMARNG. The training unit was regular Army, 4th Infantry Division. We were losing too many helicopters making the fast approach used to limit exposure in Vietnam. When all that collective needed to decelerate caused rotor decay, the pilot would run out of left pedal and the helicopter would spin right in the high LZ.

A good slow approach works in normal circumstances. When the Army needs troops delivered up high or medevaced out, this technique works well. It allows the helicopter to perform the mission at a higher DA than would be possible with even the normal apparent brisk walk rate of closure approach.

Yes, vortex ring or settling with power is a concern. It can be flown out of by increasing airspeed. Increasing just enough to quit settling causes less descent rate.

Tom Horan, city attorney for Albuquerque at the time, was commanding the 717th. He would know the particulars, but I assume the technique was approved because the 4th Infantry ran the school for regular Army as well.

I googled the mountain flying course and found both Army Aviation High Altitude Mountain Environmental Training Strategy, RA, and Colorado Army National Guard High Altitude ARNG Aviation Training Site. I was never fully aware of my situation and am now somewhat senile as well, but I am certain the instructors were regular Army when we took the course in our two week summer camp.

contactflying wrote:1976. I was in the 717th Medical Detachment to the NMARNG. The training unit was regular Army, 4th Infantry Division. We were losing too many helicopters making the fast approach used to limit exposure in Vietnam. When all that collective needed to decelerate caused rotor decay, the pilot would run out of left pedal and the helicopter would spin right in the high LZ.

A good slow approach works in normal circumstances. When the Army needs troops delivered up high or medevaced out, this technique works well. It allows the helicopter to perform the mission at a higher DA than would be possible with even the normal apparent brisk walk rate of closure approach.

Yes, vortex ring or settling with power is a concern. It can be flown out of by increasing airspeed. Increasing just enough to quit settling causes less descent rate.

Tom Horan, city attorney for Albuquerque at the time, was commanding the 717th. He would know the particulars, but I assume the technique was approved because the 4th Infantry ran the school for regular Army as well.

I googled the mountain flying course and found both Army Aviation High Altitude Mountain Environmental Training Strategy, RA, and Colorado Army National Guard High Altitude ARNG Aviation Training Site. I was never fully aware of my situation and am now somewhat senile as well, but I am certain the instructors were regular Army when we took the course in our two week summer camp.

Side note: The FAA Helicopter Flying Handbook, 2019 finally delineated and properly defined “Settling with power” and “Vortex ring state”. Also, The Vuichard Recovery technique is the most used now for “Vortex ring state”.

Last year the FAA finally agrees to use the tail rotor and lateral cyclic to get out of the down wash! I.e. Vuichard Technique. Below is an excellent example.

That technique looks like the way to recover from a fully developed vortex ring state. We never entered fully into that state. We were creeping forward, about five minutes for the approach, and if slow enough to go below glideslope we pushed forward on the cyclic enough to arrest the excess sink. If we went high on the glideslope, we dirtied up the tip path plane with some circular cyclic.

We were not at max torque, only that calibrated for 3' hover at 14,000. Our purpose was to get steeply into the confined LZ without having to touch the collective. At max torque, the collective could not increase without losing turns and crash. At too much forward groundspeed, only extra power would arrest both speed and descent descent. We didn't want to hit the trees ahead, hit the ground hard, or run out of left pedal and spin.

As we approached the mountain, a full vortex ring drop would have required a turn to miss the mountain even though we weren't taught the video technique. We didn't have any occurrence of that. Our purpose was to stay on glide path steep enough to clear near trees but not go shallow enough to have to decelerate to miss the far side of LZ trees.

Recovery at altitude provides safe experience with both stall and vortex ring state recovery. Power pitch technique to get into the LZ available is necessary to safely go down to where recovery is not probable, airplane or helicopter.

Thanks for the video. We taught forward on the cyclic for what little we knew about vortex ring state in the Army. I think the video technique is better. I didn't do any long line beyond short introduction at Rucker. Our major problem in the mountains was too fast on approach. Getting those cowboys to slow down enough to even settle a bit with power was difficult.

I was lucky enough to fly with David Trujillo in the 717th. He was a Vietnam nighthawk pilot and was the slowest on approach, the best crew trainer, and the safest pilot I ever knew.

It was a long time ago, but our semiannual Air Force seasonal weather briefing covered erroneous adiabatic rate in the mountains in summer. As the pooled valley night air heated quickly after the sun rose, there could be greater than 2 degrees temperature rise per thousand feet near the surface. I remember something about the loss of a Jolly Green Giant in a high LZ starting military interest in a mountain flying course.

Mixed up as usual. There can be less decrease in temperature than expected as we go up the mountain. I never could read charts well, or repeat data correctly.

Landing and takeoff in the mountains can be hotter than expected with resultant higher DA than planned.

Yes, I agree with you Mr. Contact information retention and interpretation in aviation is much different than let’s say reading Shakespeare or watching TV. I love cheat sheets! I have been know to scribble all over my aircraft(s)/engines with a Sharpie pen reminding me of various items. I’m a big note taker.

For extreme circumstances I made a handy little cheat sheet to tape up in the cockpit (a do it yourself placard let’s say). The placard interprets how DA would effect OGE hover @ 2100 lbs GW (this would be approximately 1.5 hours of flight time after departing at max GW with a fuel burn of 15-16 gallons/hour). After interpreting the placard I would perform an OGE power check before a confined area landing. Of course there are many variables to account for before a confined landing but, power is a good place to start making a decision!

The following information was truncated from the R44 Cadet POH:
https://robinsonheli.com/wp-content/uploads/2020/06/r44_cadet_poh_5.pdf

CHEAT SHEET R44C OGE ver #1 2020.06.11