ATIS VS. METRO
The information obtained on ATIS and from METRO each has its uses. Whereas ATIS provides
operational information not available from METRO (such as NOTAMS) and the current
weather, ATIS will not provide a forecast of the weather for the near future, when arrival might
actually be expected. A change in weather during 30 minutes can be substantial. On the other
hand, METRO can provide a 30-minute forecast and weather forecasts for more than one
location such as weather at an alternate, but does not provide the operational information
broadcast on ATIS. Both METRO and ATIS information are often needed in flight.
PILOT REPORTING WEATHER ENROUTE (PIREPS)
The Flight Information Handbook, Meteorological Information Section, contains a list of
weather reports expected of aircrew, and the PIREP FORMAT:
Location of phenomenon (station identifier, radial/DME and route segment)
Sky cover (bases, tops, and amount)
Flight Visibility and Weather
The recipient of a PIREP (ATC personnel or weather forecaster/observer) will complete a form,
which includes the information listed above. That form becomes a message report of the PIREP.
On that message, the first four items above are mandatory, so the recipient of a PIREP will
probably keep asking questions until the information in those first four items is provided (with
the likely exception of "time"). This means information for those first four items might as well
be provided initially. Two flight conditions are of such universal interest that they are routinely
reported even if they do not exist: turbulence and icing. It is common to hear a PIREP conclude
with something like "Smooth ride, no icing".