Kieran Daly and Max Kingsley-Jones/LONDON
REDUCED VERTICAL-separation minima in North Atlantic oceanic airspace are to be introduced on a phased basis from 27 March, 1997. Although the new date is three months behind the target date, it is ahead of the most pessimistic estimates.
According to the UK Civil Aviation Authority, initial separation-reduction from 2,000ft (600m) to 1,000ft will apply only to flight levels 330-370. It has not spelled out how the new altimetry minimum aviation-system performance standards (MASPS) compliance will be measured at the start of the trial.
The height-monitoring units (HMUs), to be located in the UK and Canada will not be in operation until the end of 1998, and the airlines are still waiting for information on the status of ARINC's proposed global-positioning-monitoring units. A demonstrator UK HMU is available, however, and could be used for a restricted data-collection programme. One Inter- national Air Transport Association source suggests that only a few aircraft from the majors might be checked, while all aircraft of second-tier airlines may have to be examined.
Some of the larger carriers have anticipated the service bulletin (SB)-requirements needed to meet the MASPS and have begun modification-programmes already. The SB for "classic" Boeing 747s (non -400s), for example, has been issued only within the past month, and any carrier not already undertaking the work is likely to be reluctant to do so during the busy northern summer.
One of the MASPS requirements is a "skin-waviness" check in the area of the external altimeter static-sensors, to verify that skin contours are within a variation limit. Calibration of the air-data computers to eliminate systematic errors is also required on aircraft equipped with these devices.
The airlines have been irritated by what they see as manufacturers' tardiness in addressing the MASPS.
Source: Flight International
