Monday, August 28, 2006

IFR Alternate Airports (1-2-3 Rule)

When filing an IFR flight plan, you must include an alternate destination airport when the weather forecast at your original destination predicts conditions below those specified in CFR 91.169. To help remember those conditions, you can use the 1-2-3 rule.

1 - During the time 1 hour before to 1 hour after the estimated arrival time
2 - Ceiling less than 2,000 feet
3 - Visibility less than 3 miles

If the above conditions exist, an alternate airport must be filed.

The alternate airport also has requirements that it must meet.
  • If the airport has an instrument approach published, the weather must be forecast to be (at the ETA) better than the alternate airport minima specified in that approach or the following standard conditions:

    • Precision Approach: 600ft ceiling and 2SM visibility

    • Non-Precision Approach: 800ft ceiling and 2SM visibility


Anonymous said...

Something often overlooked (As I have done) is that the first airport of intended landing must have a published instrument approach procedure or an alternate is always required (regardless of weather).

Anonymous said...

Don't forget that visibility has to be less than 3 STATUTE miles. You have to be specific on the oral exam homie.

AA5B said...

One other little technicality that is often overlooked -- the alternate, if below VFR conditions, must have an approach that can be filed as an alternate... Many airports have several IAPs that are not legal as alternate procedures due to being unmonitored... It all makes sense: you plan fuel for at least your destination, alternate, and 45 addn mins. Well, if you go miss at the original, get to the alternate and the VOR/ILS/etc. is unmonitored and *you* are the first one to discover it is down, you're screwed unless you can limp to yet a 3rd airport on the remaining fuel and land (then explain to the FAA while you filed an invalid alternate).

Art Jones said...

Ok, both the destination and the alternate weather, have to be as forecast or ....

I am just saying you need to know the weather better than ATC or NOAA.

OR you can be legal on destination and five alternates and still get slammed. I know.

Anonymous said...

Per Ohio State flight department.....for predeparture checklist.

C.I.F.F.T.R.S.S (pronounced "CIFF-TRESS")

C- Controls (free & correct)
I- Instruments (Checked & Set)
F- Fuel
F- Flaps
T- Trim
R- Runup
S- Seatbelts
S- Switches (Lights, Trnspndr,Doors, & Windows)