Fiumicino (LIRF) & Ciampino (LIRA) METARS
Only just briefly seen and read this thread. In case it helps, and before they become difficult to obtain, here are the half-hourly weather observations (METARS) for the period around the accident. The ASN report (link courtesy of Glonass, post #5, above) is unable to pinpoint the actual landing time, but it was some time between 2015 LT and 2115 LT (1915Z - 2015Z).
LIRF 022220Z 23024KT 9999 BKN035 11/03 Q0991 NOSIG
LIRF 022150Z 24025KT 9999 BKN040 11/03 Q0992 NOSIG
LIRF 022120Z 24024KT 9999 BKN040 11/03 Q0992 NOSIG
LIRF 022050Z 25025KT 9999 FEW022 BKN040 11/03 Q0992 NOSIG
LIRF 022020Z 25022G32KT 9999 SCT022 BKN040 11/03 Q0992 NOSIG
LIRF 021950Z 25023KT 9999 SCT023 SCT040 11/03 Q0992 NOSIG
LIRF 021920Z 25028G41KT 9999 SCT023 SCT040 11/04 Q0992 WS RWY 16L NOSIG
LIRF 021850Z 24024KT 9999 FEW023 SCT040 11/04 Q0992 WS RWY 16L NOSIG
LIRF 021820Z 24030KT 9999 FEW023 SCT040 11/04 Q0991 WS RWY 16L NOSIG
LIRF 021750Z 24027KT 9999 SCT023 SCT040 11/05 Q0991 NOSIG
LIRF 021720Z 24025KT 9999 SCT023 SCT040 11/06 Q0991 NOSIG
LIRF 021650Z 25023KT 9999 SCT023 SCT040 11/06 Q0991 BECMG 24018G30KT
For the uninitiated, here is a rough, plain-language translation of the 1920Z observation:
LIRF (FCO) February 2nd @ 19:20 UTC.
Wind from 250 deg (west-south-west) at 28 kts, gusting 41 kts;
Visibility 10 km or more;
(No precipitation);
Cloud ceilings (1) scattered at 2300 ft, (2) scattered at 4000 ft;
Temperature +11C, Dew-point +4C;
QNH (atmospheric pressure corrected to sea-level) 992 hPa/mb;
Wind-shear reported on approach Rwy 16L;
Trend Forecast for next 2 hours - no significant change.
I haven't flown ATRs, but can offer a few thoughts about the decision-making processes involved in flight operations when the destination weather is marginal. The main challenge was the fact that Rwy 25, the into-wind runway, was closed for maintenance. A strong-crosswind landing was unavoidable at FCO.
We do not have the TAF (aerodrome forecast) that was in force at the flight-planning stage, and which alternate airfield(s) were nominated. In flight, the captain would have decided whether or not to continue to FCO (or divert) on the basis of the above METARS, including the 1820Z and (probably) 1850Z observations, and (later) ATIS reports from ATC at FCO. On final approach, the Tower would have transmitted the wind speeds, gusts, and any wind-shear warnings.
The 1850Z METAR shows a wind from 240 (SW) at a mean speed of 24 kts, with no gust reported, but a report of wind-shear. The preceding 1820Z report gave a mean speed of 30 kts, again with no gust report, but including wind-shear for the first time. However, gusts of less than 10 kts above the mean speed are never reported on METARS, and the captain would know that. Presumably, other a/c were in the process of landing as the ATR was descending, which adds to the pressure not to divert without trying an approach to assess the conditions. An approach and go-around would be a perfectly safe manoeuvre in those conditions.
The 1920Z METAR shows the wind from 250 degrees (WSW) at 28 kts, with a recent gust to 41 kts. That represented an increase from the previous reports. 250 degrees is roughly straight across Rwy 16L, and the gust to 41 kts might have been accompanied by a shift of direction: normally a veer towards the west. The latter would represent a tailwind shear, which causes a loss of airspeed. The conditions then were certainly challenging, even to a highly experienced pilot on any aeroplane type. The next two METARS suggest that the wind moderated slightly, although there is a gust to 32 kts on the 2020Z METAR.
We don't yet know the landing time, or if it was off the first approach.
Here are the relevant observations for the nearby Roma Ciampino, which - if open - is normally the preferred alternate for Fiumicino. It has a single runway, aligned 15/33. If the ATR had diverted there at an early stage, it might have arrived at about 1945Z. For whatever reason, the wind is much lighter there, apparently never exceeding a 20-knot crosswind component.
LIRA 022115Z 22010G24KT 9999 SCT017 SCT030 10/02 Q0992
LIRA 022045Z 23012KT 9999 SCT017 SCT030 10/04 Q0992
LIRA 022015Z 23011KT 200V260 9999 SCT017 SCT030 10/04 Q0992
LIRA 021945Z 25008G20KT 210V290 9999 SCT017 SCT030 10/03 Q0992
LIRA 021915Z 25009G22KT 210V300 9999 SCT017 SCT030 10/04 Q0991
LIRA 021845Z 24015G26KT 9999 SCT017 SCT030 10/04 Q0991