R172K Approach Configuration

Matt Whiting wrote:

I like the recommendations made in Peter Dogan's book, The Instrument
Flight Training Manual. However, as your instructor said, there is no
single right power setting. If you assume no wind conditions, then a
90K approach speed works well as that yields close to 90 knots ground
speed (not exact due to the descent angle, but really close) which
matches up with one entry in the time charts for timed approaches.


Don't forget that 90 K indicated airspeed only equals 90 knots ground speed at sea level on a standard
day with no wind. At higher altitudes, your TAS (and GS depending on the wind) will be significantly
higher.

Regardless, I agree with most of your post. I find the Dogan-style performance numbers are a good
starting point, and help to get configuration changes stabilized. It does then require tweaking to suit the
specific conditions, though.

Mike

Mike Adams wrote:
Matt Whiting wrote:


I like the recommendations made in Peter Dogan's book, The Instrument
Flight Training Manual. However, as your instructor said, there is no
single right power setting. If you assume no wind conditions, then a
90K approach speed works well as that yields close to 90 knots ground
speed (not exact due to the descent angle, but really close) which
matches up with one entry in the time charts for timed approaches.



Don't forget that 90 K indicated airspeed only equals 90 knots ground speed at sea level on a standard
day with no wind. At higher altitudes, your TAS (and GS depending on the wind) will be significantly
higher.

Regardless, I agree with most of your post. I find the Dogan-style performance numbers are a good
starting point, and help to get configuration changes stabilized. It does then require tweaking to suit the
specific conditions, though.

Yes, very true. I was trying to keep it simple and most people in the
USA fly from airports that are 2,000' MSL or less which doesn't
introduce huge errors due to non-standard conditions. However,
certainly if you are landing in Leadville, then it is a big deal.

Matt