New Approach Invites Wake Turbulence Encounters

Air Safety Week, Dec 20, 2004

For all of these reasons, ALPA has said it is "unable to support" the proposed SOIA at Cleveland and asserts that "significant safety concerns inherent in the FAA's proposal" need to be resolved. Any ALPA support of SOIA at Cleveland "hinges on the results of a comprehensive safety case," the pilots' union said in its Nov. 11 letter to the FAA.

A number of things could be done to resolve the impasse. Moving the LDA to runway 24R would go far to address the ALPA concerns. By this move, the threshold relative to the missed approach point (MAP) would be altered, and pilots flying an LDA approach to runway 24R would be higher than pilots making an ILS approach to runway 24L.

Installing wind profiler technology at Cleveland would provide air traffic controllers with the strength and direction of winds at altitude (see ASW, Nov. 25, 2002).

Extending the far end of runway 24L would eliminate the staggered touchdown point, enabling the touchdown points for runways 24L and 24R to be lined up. However, such a runway extension is years away.

In a Sept. 14 letter to the FAA obtained by ASW, Continental Airlines [CAL] expressed its preference for placing the LDA on runway 25R but, pending its preference, suggested a number of interim measures could be taken. The carrier has a significant RJ operation at Cleveland. It suggested:

* A 1.5 NM rather than 2 NM separation for the following LDA aircraft relative to the leading ILS aircraft. This 25 percent reduction in permissible trailing distance would provide an added safety margin. Indeed, Continental suggested that with a software modification to the PRM (precision runway monitor) radar, the pairing requirement could be programmed into the PRM display, easing controller workload while enhancing controller situational awareness.

* Discontinue SOIA procedures when the crosswind component exceeds 20 knots at the missed approach point (MAP) altitude. At the same time, periodically solicit wind reports from pilots and increase the frequency of such solicitations as a function of increasing wind speed.

* Sequence all small and "commuter prop" aircraft and RJs to the straight-in ILS approach to the extent practical.

Continental also urged the FAA to assure ALPA that the target level of safety can be met until such time as the LDA can be relocated to runway 24R.

An FAA official said discussions are ongoing about the SOIA situation at Cleveland. Meetings involving various FAA offices and ALPA were held last week, and the results of these proceedings - and any decisions emanating from them - will be duly reported.

(For more on UHF Doppler wind profiler technology , see www.ofcm.gov/r14/front.htm. For a NavCanada June 2004 overview of SOIA, see www.navcanada.ca/ContentDefinitionFiles/IFIS/Powerpoint/Session_5/Implementation _of_SOIA_Procedures_Courtney_Barbeau.pdf. For a UK perspective on SOIA, see www.caa.co.uk/docs/33/FOD200406.pdf. U.S. pilots have previously expressed their concerns about the safety of SOIA, see ASW, July 26, 1999)