aircraft to transition from level flight (at MDA) and very high thrust settings, to a stabilized approach and touchdown in 15 to 20 seconds (the distance covered in one mile visibility at 180 knots)" because of the size of the aircraft and approach speeds at which the nonprecision approaches are flown.
1.18.4.2 Approach Chart Terrain Depiction
According to testimony at the Safety Board's public hearing by the Senior Corporate Vice President of Flight Information Technology and External Affairs for Jeppesen Sanderson, Inc., approach chart manufacturers use various methods to depict obstructions and high terrain on published approach charts. Some en route charts and the plan view of some terminal approach charts use contour lines and color shading to depict various height gradients with symbols for high obstructions. Other charts use broader colored areas for terrain depiction and specify a minimum sector altitude for obstacle clearance in segmented areas around the airport. In some instances, terrain may be depicted on the plan view of some approach charts but not on other charts published by the same manufacturer.
Currently, no chart publisher depicts terrain or obstructions on the profile view, which depicts the inbound course descent profile from the IAF to the landing or MAP. Further, the FAA Terminal Instrument Procedures (TERPS) manual contains no requirement for a standardized format that chart manufacturers must adhere to when depicting terrain on an approach chart, except for the requirement to depict the height of certain obstructions.
The Jeppesen Sanderson official testified that "the Agana ILS 6 Left approach did not have terrain [depicted on the chart]...because through the agreements that we've had with our airlines, seminars in the airline community, as well as a lot of the general aviation input, it is believed by Jeppesen that...there should be criteria because you don't want terrain to be on all charts; you want it there when it's significant." The official added that, for Jeppesen to depict terrain on a chart, there needs to be at least one elevation that is 4,000 feet or greater above the airport in at least one plan view of the airport or, if there is one elevation that is 2,000 feet above the airport within 6 miles, then contour lines need to start at the nearest 1,000 feet to the airport elevation and appear at 1,000-foot intervals all the way up to the top altitude that is depicted.
The Jeppesen official's testimony discussed the difficulties of obtaining accurate worldwide terrain data through public sources. The official said that inaccurate information was one of several reasons for not providing terrain information on the charts. The official further stated that there are many sources for terrain information but that the information needs to be publicly available so that chart manufacturers can have ready access.
The Chief Engineer of Flight Safety Systems at AlliedSignal, Inc., testified at the Safety Board public hearing about the acquisition and accuracy of terrain data. The official indicated that terrain data needs to be collected to build the database not only for chart manufacturers but also for companies that are incorporating such data into enhanced
