soft field/ short field landing advice
- Thread starter Ngrossman
- Start date
bdhill1979
Gone West
That is one thing I have seen more than one examiner yell about.
You are required to use either the book speed or 1.3 Vso (I don't have my PTS in front of me but I believe that is what it says).
And don't forget that the PTS requires the short field to be simulated with a 50 foot obstacle at the approach end of the runway.
If you briefed it before hand and could explain it than I can't see why. However, the examiner may ask you to just stick with the published speeds, either way I would brief it on the ground and find out what they want.
Oh and as was so nicely pointed out about CAS, the stall speed of 33 IAS but the book only gives 40 IAS as 47 CAS. Knowing that the lower the speed the more inaccurate the system we can assume 10 knots increase for 33 to give a little safety buffer. 43 * 1.3 = 55.9 So basically 55 is the lowest I would go per that information, sorry for my misinformation before.
tgrayson
New Member
Possibly. The PTS provides a margin of +10/-5 knots around the recommended speeds, and 55 is just slightly outside the range; and it doesn't give you any margin of error.
You could make the argument that since you're less than max gross, you have a reduced stall speed and hence can safely fly slower speeds. Although true, the difference won't amount to 6 knots.
I recommend flying published airspeeds.
Contrary to popular belief, they are not aliens, they are people just like all of us. Don't do anything crazy with them, be respectful, dress appropriately, and try to be professional and you shouldn't have any problems with any DPE.
tgrayson
New Member
You're talking about indicated airspeeds, which are grotesquely inaccurate at low speeds.
You are able to bring it that low via the IAS, which the slower you go the more erroneous the IAS is to actual speed. It may say 20 but I assure you that you are still over 33 (leaving some dynamics out for simplicity) or you would be stalled.
As bd said though, the accepted is usually book value or 1.3 * Vso which is the number I gave you. If you brief before hand and your DPE says no to 1.3 than you stick with book value, no harm no foul. Surprising the DPE is a no no, but there is nothing wrong with discussing a procedure you wish to use in flight while safely on the ground.
bdhill1979
Gone West
Because the instrument is not perfectso then i beg to ask why the tape doesn't show cas and why it shows ias would it not be safer to be indicating the more accurate of the two?
Read up on the errors associated with the Airspeed indicator
tgrayson
New Member
so then i beg to ask why the tape doesn't show cas and why it shows ias would it not be safer to be indicating the more accurate of the two?
Primarily due to the location of the static port on the aircraft. It's very difficult to find a location which accurately reflects the ambient static pressure, due to the influence of the fuselage on the static pressure in the immediate vicinity of the aircraft. That said, the instrument is pretty accurate at normal flight speeds, so I'm skeptical it's much of a safety issue.
I was under the impression that it was more a result of the AOA of the wing as it directly effects the angle that the pitot tube hits the relative wind.
For high power at slow speeds though I could see the airflow from the prop over the fuselage, and therefore over the static port, sucking air out of the port and thus leaving it thinking it is at a higher altitude than it is. Wouldn't that effect result in the speed reading higher though? Now I confused myself dammit.
Can you give more details?
as shdw just said thats kinda interesting and can you give us more details tgray? As i was thinking less about the pitot tube and relative wind , but more as AoA and CAoA relate to CL but thats completely off topic unless we start relating it energy control and transfer due to the physics of the airplane
bdhill1979
Gone West
I have had way too many beers to stay in this conversation, but I will say the disruption of the air at the static port does have a much larger impact than at the Pitot. Try opening the alternate static and opening all the vents and windows and see what it does.
bdhill1979
Gone West
Tell her you read it on the internets, that will convince her.
:beer: Cept for me it is triple shot margaritas
:rotfl::rotfl:
