Density Altitude ?

[clarkefarm]

I am not sure that I will ever get my 9A here but have ended up at Cuzco in Peru en route to Lake Titicaca.
Was a bit worried about the elevations considering the Australian Civil Aviation Safety Authority mandate oxygen at 10,000'. Cuzco is about 11,000 and Lake Titicaca 12,500.
Turns out that this is the least of it. Because it is sunny and warm at this time of the year the DAs look really horrible. I think that todays numbers indicate 13,739' for Cuzco and 15,129' for Juliaca (SPJL) which services Lake Titicaca. Needless to say I have not seen too many C172s around.
I guess that the good part of the experience is that I still seem to be breathing OK during the day and able to function well enough. The bad part is handling slower breathing at night.
The heavy metal drivers might be able to confirm this but I expect the approach and rotate speeds at Juliaca to be fairly exciting. The aircraft used are Airbus A319s (I think).
Rupert Clarke

 

[F1R]

Your indicated airspeed (IAS) numbers for rotation, best glide, stall and approach should remain unchanged, however your ground speed will be a lot faster. Likewise take off roll will be considerably LONGER.


I am thinking it would be a great place for a turbocharged lycoming if ever there was one. I was OK for several days at Cuzco and Machu Pichu, however I was constantly hypoxic at Titicaca for as many days as I was there. Rotten headache, weak and useless.


I would not consider flying there without O2. I do not recall any piston AC at either airport.

 

[BobTurner]

Your indicated airspeed (IAS) numbers for rotation, best glide, stall and approach should remain unchanged, however your ground speed will be a lot faster. Likewise take off roll will be considerably LONGER.


I am thinking it would be a great place for a turbocharged lycoming if ever there was one. I was OK for several days at Cuzco and Machu Pichu, however I was constantly hypoxic at Titicaca for as many days as I was there. Rotten headache, weak and useless.


I would not consider flying there without O2. I do not recall any piston AC at either airport.

I'm sure you meant the true airspeed will be higher. Ground speed will depend on the wind.

 

[N941WR]

Your indicated airspeed (IAS) numbers for rotation, best glide, stall and approach should remain unchanged, however your ground speed will be a lot faster. Likewise take off roll will be considerably LONGER.


I am thinking it would be a great place for a turbocharged lycoming if ever there was one. I was OK for several days at Cuzco and Machu Pichu, however I was constantly hypoxic at Titicaca for as many days as I was there. Rotten headache, weak and useless.


I would not consider flying there without O2. I do not recall any piston AC at either airport.

I'm sure you meant the true airspeed will be higher. Ground speed will depend on the wind.

No, he was correct (as are you). The indicated airspeeds will remain the same but your speed across the ground, assuming no wind, (true airspeed) will be much greater. Thus, when he comes in to land, he will be hauling and he will have to get a much higher ground speed than at lower altitudes to get his airspeed indicator to read high enough to rotate and climb.

 

[BobTurner]

No, he was correct (as are you). The indicated airspeeds will remain the same but your speed across the ground, assuming no wind, (true airspeed) will be much greater. Thus, when he comes in to land, he will be hauling and he will have to get a much higher ground speed than at lower altitudes to get his airspeed indicator to read high enough to rotate and climb.

Yes, ground speed equals true airspeed with no wind. But if he has a strong headwind, his ground speed can be low. But his true airspeed will be higher than at sea level. If that's not what I said, that's what I meant!

 

[longranger]

I wonder if the airlines that operate in there run special tires? Dad used to comment about approaching maximum tire speeds on B-737's at Denver on a hot day. Of course, that was in the 1970's and 1980's...

 

[paul mosher]

nope

I wonder if the airlines that operate in there run special tires? Dad used to comment about approaching maximum tire speeds on B-737's at Denver on a hot day. Of course, that was in the 1970's and 1980's...

Nope.

But when I was with Braniff they used the DC-8-62 for high altitude airports. Short fuselage and long wing of a -63.

 

[jrs14855]

tires

My recollection is that up through the mid 80's the standard tire for the DC9 had a limit of 225 STATUTE. On a zero flap takeoff at 5000' elevation on a hot day we would be right at the tire limit. 12,000 feet from start of takeoff to rotate, 1500' of runway remaining at rotate, main gear left the ground with about 500' remaining. This was not a runway limited takeoff. On shorter runways I have gone between the threshold lights just as the main gear left the ground. These were special increased speed takeoffs developed by Douglas. We eventually got JATO, strictly standby, only used in case of engine failure. My company and Aeromexico were the only JATO equipped DC9's that I know of.

 

[jrs14855]

Elevation

There is an ancient Inca sacrificial burial site in the Andes at 22,000'. There are numerous articles about this. There is evidence that the Incas rested at 17,000' to acclimate to the high altitude. Three children buried at one site were discovered around the late 90's.

 

[paul mosher]

225

225 as I recall. We had to replace them if they exceeded it. Don't remember doing it though. No flap landings on 727 usually resulted in blown thermal plugs from braking.

 

[Nickb145]

I'm reviving this discussion. I too am curious about DA. What kind of Density Altitude are you guys not comfortable taking off at? With a Io-375 on our 8 a 7,000Density altitude should not be too much of an issue if i'm the only occupant with little baggage, just have to watch temperatures.

 

[Mel]

I've flown my -6 out of Leadville, CO with a F/P wood prop when the DA was over 13,500'. No problem. Yes, I used a considerable amount of runway, compared to home, but there was plenty remaining.
The RVs handle DA quite well. The -9 should do even better than the -6.

 

[skylor]

Density Altitude

I'm reviving this discussion. I too am curious about DA. What kind of Density Altitude are you guys not comfortable taking off at? With a Io-375 on our 8 a 7,000Density altitude should not be too much of an issue if i'm the only occupant with little baggage, just have to watch temperatures.

I've flown my -8 a few times out of airports with the DA > 10,000', the most recent of which was out of Mammoth last Thursday with takeoff weight @ 1800 lbs. This was pretty much a non-issue for my IO-360/Hartzell BA prop powered 8. Even at that altitude performance is still better than most Spam Cans at sea level.

Skylor
RV-8

 

[Caveman]

We just left Leadville Friday

I'm reviving this discussion. I too am curious about DA. What kind of Density Altitude are you guys not comfortable taking off at? With a Io-375 on our 8 a 7,000Density altitude should not be too much of an issue if i'm the only occupant with little baggage, just have to watch temperatures.

The wife and I attended the 4th of July fly-in at Leadville a few days ago. I topped off with fuel and we had enough luggage on board for a 3 day Jeep off-road vacation. We were right at gross weight when we left around 2 pm and headed to Buena Vista. D.A. was not an issue for our TMX-IO360m1b w/ BA Hartzell. The runway is over 6000' long and I doubt we used 2000' of it. I did lean for best power before take-off.

Beautiful scenery up there, and after 6 years of flying and gathering scratches and wear and tear the 7 still drew a mini-crowd.

 

[Greg Arehart]

I learned to fly at Leadville, and never had an issue with an old tired C172 (with the Conti O-300!) as long as there were only two of us in the airplane. With the RV9 a few years ago when I returned to visit, it was not an issue in midsummer at DA of 13-14k. I would not hesitate to land/take off at a DA of 15-16k, as long as I had a decent length of runway (say, 2000-2500 feet) in my 9 (with an IO360).

Greg