Saturday, November 14, 2009

Did I Choose Wisely?

In yesterday's post I discussed the forecasts for KVKX (my home airfield) and my decision to not fly down from KBDR and to instead take the train. So, I'm curious about what I would have encountered if I had decided to fly.

I've learned over time that the weather at nearby Andrews AFB (KADW) closely approximates conditions at KVKX. Here are the METARS (slightly edited for space) for KADW surrounding what would have been my ETA:
KADW 140015Z AUTO 01011KT 7SM -DZ OVC007 11/10 A2987 RMK AO2 RAB0001E0012
KADW 140005Z 01013KT 5SM -RA BR OVC008 11/10 A2986
KADW 132358Z 01012G19KT 7SM -DZ OVC006 11/10 A2986 RMK CIG 005V021
KADW 132355Z 01014G19KT 8SM -DZ OVC006 11/10 A2986 RMK CIG 006V021 T01120101
KADW 132353Z 01013KT 8SM -DZ OVC006 11/10 A2986 RMK CIG 006V021
KADW 132348Z AUTO 01013KT 8SM -DZ OVC009 11/10 A2987 RMK CIG 006V021

There are a couple of interesting things to note. First, we see a 1 degree C spread between the temperature and the dew point, so low ceilings are unsurprising. Over the half hour covered, the prevailing ceiling varies from 600 to 900 feet MSL with some readings as low as 500 (see, for example, "RMK CIG 005V021" in the 2358Z METAR).

With the MDA for the one approach at KVKX at 680 feet MSL, it looks like there was a good chance of my being forced to divert to my alternate, Manassas (KHEF) (which was reporting an overcast at 2000 feet MSL at the time). Since that would have entailed considerable logistical annoyance, I guess I chose widely.

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