On the Design of Flight-Deck Procedures - Intelligent Systems ...

to maintain this speed up to 10,000 by adjusting pitch and ignoring the flight director pitch bar. This techniquehad proven to give a much smoother level off and acceleration to climb speed.Our takeoff had been behind an aircraft and slightly after takeoff we had experienced a little turbulence which weassumed was from the proceeding wide body. The captain decreased pitch to stay out of his wake while we bothwere looking outside of the aircraft in an effort to see the wide-body. Unable to acquire the aircraft, the captain'sscan returned to his ADI and he began to follow the pitch bar, which led him to accelerate beyond 250 knotsAircraft speed was noted and reduction begun. Aircraft accelerated to approximately 320 knots (ASRS ReportNo. 155390).For the sake of explaining how policies affect technique, let us assume that the airline had a policy ofbacking up critical tasks with other modes or aids. Examples of procedures that stem from such policywould be a requirement that visual approaches should be backed-up by the ILS and/or ADF, and aprocedure specifying that pilots of automated cockpits track LNAV heading by appropriately updating theMCP heading display whenever the aircraft changes heading. If such a policy is specified, then one canargue that both of the auto-leveloff techniques that we have detailed above violate this policy. Such apolicy provides that a failure of a certain system component does not leave the crew empty handed. Theintent is that the crew choose their primary mode, but also configure other modes to which they or thesystem can default to. The same policy can be applied for automation, i.e., configure all the appropriateautomation modes so that if one fails, the pilot or the system can easily default to another. As can beseen in the ASRS report above, the 300-knots technique does not comply with this policy.Similar policies of backup as related to use of automation can be seen in the following altitude procedure:“Do not set expected altitudes in the MCP/altitude alerter. Set the most restrictive altitudes as opposed tothe top/bottom altitudes.” The concept here is if the automation (VNAV) fails, then the autopilot will notcross the hard altitude set in the MCP window. At other airlines this is done differently: during the stepdowndescent the altitude window is set for the lowest restriction. The reader should note that bothprocedures stem from a different operating policy of the autoflight system.Let us examine another technique from a policy standpoint:After takeoff the aircraft accelerated to 250 knots and flaps were retracted. While in a tight (30 degree bank) turn,ATC requested: “slow to 230 knots.” The captain (PF) disengaged the autothrottles, reduced power and pitch,and maintained 230. After being cleared back to 250 knots he re-engaged them. At cruise, we asked him whydisengaged the autothrottles. He replied that the clean (no flaps) maneuvering speed was 245, therefore, had hedialed 230 knots in the speed window, the alpha protection logic of the autothrottles would have maintained aspeed of 245. Since he did not want to “dirty” the aircraft by extending slats, he choose to disengage theautothrottles (and with it, the alpha floor protection), reduce bank angle, and maintain 230. He stated that thiswas not per SOP. Nevertheless, he felt that other built-in protection of the aircraft would have prevented himfrom reaching buffet speed.To answer the question of whether or not this example represents an acceptable technique, one mustcompare it with the company's stated policies. If this technique is compared to the policy, discussedabove, of backups and defaults for using automation, then, of course, it is not acceptable.To summarize, our position is that a technique not only must conform to the procedure -- it must alsoconform with the company policy. The fact that a technique does not violate a written procedure(produces no “∆”) does not necessarily make it acceptable. The technique may still entail an unessentialrisk and inefficiency. Every technique must therefore conform to both procedures and policies (andpossibly philosophies).5.7.4 Technique and ManagementWhat view should management take of pilots developing their own techniques? Does thesuperimposition of “personal” technique on SOPs represent a compromise with standardization? Onceagain the answer is to be found in the “Four-P” model. Management must develop a philosophy thatgoverns the freedom of the pilot to improvise, and from this philosophy will flow company policies thatwill state exactly what the company expects of the line. Our own view, of course, is to return to thedefinition of “∆.” If the techniques employed on the line lead to practices that are consistent with thepublished procedure and policies, then “∆” is zero and management should not interfere.27