120 that you wouldn’t want them extended if a go-around became necessary. (Surprisingly, many speed-brake systems do not auto-retract when go-around [GA] thrust is applied.) Secondly, most operators require that f light crews establish a stabilized landing approach by 1,000 feet AGL, meaning the aircraft is properly configured for landing, “on-speed” (VREF to VREF +10), and descending at a vertical speed of 500–1,000 fpm making speed-brake use unnecessary. In other words, if you still feel the need to use speed brakes below 1,000 feet, you’re probably outside normal approach parameters and would likely be wise to discontinue the approach and execute a go-around or missed approach. Aircraft autopilot systems have specific limitations that vary widely among manufacturers and aircraft operators. However, there are a few autopilot limitations common to all aircraft that you should be aware of. For instance, since most autopilot systems counter aileron trim inputs and there’s danger of excessive roll when the autopilot is subsequently disconnected, the use of aileron trim with autopilot engaged is commonly prohibited. Another common autopilot limitation covers how soon after take-off autopilot use is authorized. (Restrictions of 200 feet, 500 feet, or 1,000 feet above ground are common.) Autopilot use on approach is also limited to certain altitudes, depending on the type of approach you’re flying and how many autopilots are available as backup. (Many aircraft have two or three autopilots installed.) Additionally, autopilots with auto-land capability have more restrictive maximum crosswind, tailwind, and headwind limits than the limitations of the aircraft itself. Also, most aircraft are only authorized to auto-land with landing flaps extended; auto-landing with any other flap setting is prohibited. The autopilot limitations specific to your aircraft will be covered in ground school and must be committed to memory. Fuel systems and fuel management procedures also have numerous aircraft-specific limitations. Common to all fuel systems are maximum and minimum fuel temperature limitations. Also, all turbine aircraft have maximum allowable fuel imbalance between wing tanks, and may have different limits for takeoff and landing. Fuel management limitations also define which tanks may be used for takeoff or landing (e.g., takeoff with the center tank supplying the engines is prohibited).
THE TURBINE PILOT’S FLIGHT MANUAL
Aircraft maximum operating altitude is the maximum altitude up to which flight operation is allowed, as limited by structural, powerplant, pressurization, load limits, or equipment characteristics. Maximum operating altitude is also dictated by safe operating speed margins between stall speed and high-speed buffets as functions of altitude, angle of bank, and aircraft gross weight. (See Chapter 15, Aerodynamics of High-Speed/High Altitude Aircraft, for further explanation.) Some aircraft systems may have maximum altitude limitations for operation that are lower than the aircraft maximum operating altitude. Maximum flap operation altitude is the maximum altitude that an aircraft may be flown with flaps extended, or while flaps are being extended or retracted. Flight above this altitude requires a clean wing; no flaps or slats may be extended. Maximum Altitude for Auxiliary Power Unit (APU) operations. Most auxiliary power units have maximum altitude operating limitations that are lower than the aircraft’s maximum operating altitude. Some APU’s feature additional altitude restrictions such as maximum altitude for APU start, maximum altitude for APU pneumatic use, or maximum altitude for APU electrical use.
Operational Limitations There are numerous limitations you will be required to be familiar with which are operational in nature, rather than relating to aircraft systems per se. Your company operations and flight manuals will thoroughly address such limitations. Let’s take a look at some of the major operational limitations with which you will need to be familiar. Minimum flight crew is the number of crewmembers considered sufficient by the FAA to safely operate the aircraft considering each individual flight station’s workload, accessibility, and ease of operation of necessary controls. This required minimum flight crew number may change depending on the nature of the flight operation. The FAA also defines a minimum number of flight attendants required on board the aircraft during each leg carrying passengers. Aircraft seating less than 20 passengers are not required to carry flight attendants. For seating configurations of 20 or more passengers, the minimum number of flight
