Density altitude

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Density altitude

Author	Message
BearLS	BearLS posted 8/28/2018 12:47:50 PM Post Details Share Post
Group: Forum Members Posts: 9, Visits: 226	+x Tim Dawson - 8/22/2018 4:20:17 PM Chris, you forgot to say exactly why it would be useful. What exactly do you use the DA number for, once you have it? Density altitude is the critical parameter to calculate the take off distance and the climb rate. The most dramatic example i know is Samedan LSZA at 5600 ft altitude. Before you are allowed to fly there you must pass an examination in internet. The calculation of the density altitude is an important part of it. The reason for that is that there where to many deadly accidents at take off. Most people forget that the density altitude is also important at higher altitudes in terms of the climb rate. In the last weeks we had rather high temperatures in Switzerland. At least in two cases Swiss Transportation Safety Investigation Board (STSB) had to get active due to deadly accidents which are absolutely linked to the density altitude, see https://www.sust.admin.ch/inhalte/AV-berichte/HB-HOT.pdf (20 persons killed) and https://www.sust.admin.ch/inhalte/AV-berichte/HB-KEE_2.pdf (4 persons killed, I knew the pilot and the plane very well). To increase the awareness for the density altitude it would be very helpful to get the density altitude in each METAR reported by SkyDemon. Yes, I am aware the we mountain pilots will probably never get the desired improvement, since we are a minority among the customers of SkyDemon. Very sad situation.
	Reply Like 3
Daniel Sinn	Daniel Sinn posted 9/4/2018 8:08:37 AM Post Details Share Post
Group: Forum Members Posts: 44, Visits: 13	+x BearLS - 8/28/2018 12:47:50 PM +x Tim Dawson - 8/22/2018 4:20:17 PM Chris, you forgot to say exactly why it would be useful. What exactly do you use the DA number for, once you have it? Density altitude is the critical parameter to calculate the take off distance and the climb rate. The most dramatic example i know is Samedan LSZA at 5600 ft altitude. Before you are allowed to fly there you must pass an examination in internet. The calculation of the density altitude is an important part of it. The reason for that is that there where to many deadly accidents at take off. Most people forget that the density altitude is also important at higher altitudes in terms of the climb rate. In the last weeks we had rather high temperatures in Switzerland. At least in two cases Swiss Transportation Safety Investigation Board (STSB) had to get active due to deadly accidents which are absolutely linked to the density altitude, see https://www.sust.admin.ch/inhalte/AV-berichte/HB-HOT.pdf (20 persons killed) and https://www.sust.admin.ch/inhalte/AV-berichte/HB-KEE_2.pdf (4 persons killed, I knew the pilot and the plane very well). To increase the awareness for the density altitude it would be very helpful to get the density altitude in each METAR reported by SkyDemon. Yes, I am aware the we mountain pilots will probably never get the desired improvement, since we are a minority among the customers of SkyDemon. Very sad situation. I totally agree
	Reply Like 2
ArnaudC	A ArnaudC posted 10/3/2018 3:05:16 PM Post Details Share Post
A Group: Forum Members Posts: 77, Visits: 133	For quick MET readouts I use the AeroWeather app. It calculates DA. Most POHs have a PA/DA conversion chart at the beginning of section 5. Cruise performance charts can be used for it as well. As mentioned by T67M above, unless T/O/climb/LDG performance calculations are made in SD as well, you still have to open your POH. Displaying only the DA without the rest is only semi-useful. +x T67M - 8/25/2018 4:34:08 PM What you need for them is (generally) pressure altitude, and that's trivial to obtain with no calculation whatsoever (set 1013.25 in the Kohlsmann Windows and read the altimeter). It's easier to set the field elevation and read the PA in the window. Potato potato.
	Reply Like 1