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From NASA's Aviation Safety Reporting System�
Number 189
February 1995
A Frequency of Digits
Among the most famous one-liners from the black-and-white movie era was W.C. Fields’ sly flattery of Mae West, as he admired her hand: “Ah, what symmetrical digits you have!” Yet digital symmetry–identical or very similar number elements used in radio frequencies–is a less amusing subject to many pilots, especially when similar digits are assigned to ILS frequencies for parallel runways. The limited number of ranges available for ILS frequency assignments is undoubtedly one reason that repetition of numbers, or use of similar numbers, occurs. Regardless, a recent report to ASRS from an air carrier pilot illustrates the problems that can ensue when a flight crew fails to verify navigation radio settings because of high workload during the final approach: 18R/L 17R/L 111.9 / 110.55 Dallas-Ft. Worth 111.35 / 110.3 Dallas-Ft. Worth Miami International appears to be the only airport with a double whammy–its easterly parallel runways are assigned frequencies with identical first three digits, and the reversed, westerly paral lel runways are also assigned frequencies with identical first three digits. Frequencies with similar or identical number elements can cer tainly play a role in incidents such as the one above reported to ASRS. However, careful selection and visual verification of radio frequencies (especially with electronic displays), combined with verbal callouts of the navaid frequency, go a long way toward preventing these types of incidents.
■ We had been deviating around cells since we had reached the
southern tip of Florida. We were given an approach clearance for the ILS to 9R. The First Officer [F/O] was flying the aircraft and I was concerned with a cell that had been on the field and at the time was located at the boundary of the airport. I had looked at the F/O's radios and had seen the proper inbound course dialed in and a frequency of 110-something. Before we got to the initial approach fix, the Approach Controller told us to turn right 20 degrees and intercept the 9R localizer. It was at this time I real ized that my F/O had tuned in 110.3 instead of 110.9, the localizer for 9R. We had initially been on the localizer for 9L. For tunately, approaches were not being made on that runway at the time. I think a major contributing factor to this incident is the fact that both localizer frequencies for landing in the same direction start with 110 (110.9 for 9R and 110.3 for 9L). Interestingly enough, both localizer frequencies landing to the west start with 109 (109.1 for 27R and 109.5 for 27L). Our reporter wrote that he had never previously encountered this situation. However, a cursory look through the approach plates for a number of major metropolitan airports revealed quite a few instances in which parallel runway ILS frequencies are similar. Some parallel runway ILS frequencies have the same first three digits, and only the decimal digits differ: 33R/L 11R/L 8R/L 111.95/111.7 110.3/110.7 109.9/109.3 Baltimore-Washington Int’l Minneapolis-St. Paul Atlanta
From Angels to GRUMPs
CALLBACK’s readers occasionally like to embellish on stories and safety tips offered here, and this was the case with our De cember ‘94 issue (#187), which inspired several letters of interest. In response to our “Guardian Angels” item about a Cherokee Six internal fuel drain actuator that was accidentally activated by a passenger, one pilot shared this more uplifting experience:
✍ I owned a converted Twin Comanche. I had been to Florida,
from where I filed IFR in lousy weather back to North Carolina. Level, at altitude and in clouds, I shifted to the outboard tanks, and shortly thereafter the right engine went dead, windmilling. The fuel gauge showed a full tank. I shifted back to the main tanks, and the engine started up again. During the preflight I had drained a not insignificant amount of water from the right outboard tank (there had been heavy rains in Florida and I had never learned that I should have exchanged the short neck gas caps for the tighter long neck). So I decided to switch back to the outboard tank and then pull the fuel drain which fortunately is inside the cockpit. I didn’t have to drain for long before the engine again was running as it should. Inboard fuel drains can save the day... Several readers responded to our article on “GUMP,” offering their own variations on this familiar acronym. First, from a pilot who advocates GRUMP:
One ILS frequency was found with identical decimal digits, and nearly identical first three digits: 2R/C 111.75/110.75 Nashville, TN
Dallas-Ft. Worth has an interesting situation with its parallel cluster “Right” ILS runways assigned the same first three digits, and its parallel cluster “Left” ILS runways also assigned the same first three digits:
✍ Somewhere in my past, someone recommended adding an “R” for Radio, making it GRUMP...particularly when flying VFR from a field using the CTAF to another [field] which uses a different CTAF frequency. [In these situations] it is easy to forget that all the chatter coming over the radio is not on the [frequency] you need. At controlled fields it is less likely that the radio will be mistuned, however frequency changes are easy to miss.
Another correspondent likes GUMPS–with the “S” standing for “Seatbelt.”
ASRS Recently Issued Alerts On...
Spoiler delamination visible only inflight on a B737-500 Alleged design flaw in an L-1011 fuel shutoff switch guard Questionable ATC sequencing of a B-727 behind a B-757 Flight/ground crew illness attributed to rain repellent leak Inadequate length Flight Attendant seatbelts on a DC9-30
A Monthly Safety Bulletin from The Office of the NASA
Aviation Safety Reporting
System,
P.O. Box 189,
Moffett Field, CA
94035-0189
December 1994 Report Intake
Air Carrier Pilots General Aviation Pilots Controllers Cabin/Mechanics/Military/Other 1980 630 70 27
TOTAL
2707
飞行翻译公司 www.aviation.cn 本文链接地址：美国ASRS安全公告CALLBACK cb_189.pdf
From NASA's Aviation Safety Reporting System�
Number 189
February 1995
A Frequency of Digits
Among the most famous one-liners from the black-and-white movie era was W.C. Fields’ sly flattery of Mae West, as he admired her hand: “Ah, what symmetrical digits you have!” Yet digital symmetry–identical or very similar number elements used in radio frequencies–is a less amusing subject to many pilots, especially when similar digits are assigned to ILS frequencies for parallel runways. The limited number of ranges available for ILS frequency assignments is undoubtedly one reason that repetition of numbers, or use of similar numbers, occurs. Regardless, a recent report to ASRS from an air carrier pilot illustrates the problems that can ensue when a flight crew fails to verify navigation radio settings because of high workload during the final approach: 18R/L 17R/L 111.9 / 110.55 Dallas-Ft. Worth 111.35 / 110.3 Dallas-Ft. Worth Miami International appears to be the only airport with a double whammy–its easterly parallel runways are assigned frequencies with identical first three digits, and the reversed, westerly paral lel runways are also assigned frequencies with identical first three digits. Frequencies with similar or identical number elements can cer tainly play a role in incidents such as the one above reported to ASRS. However, careful selection and visual verification of radio frequencies (especially with electronic displays), combined with verbal callouts of the navaid frequency, go a long way toward preventing these types of incidents.
■ We had been deviating around cells since we had reached the
southern tip of Florida. We were given an approach clearance for the ILS to 9R. The First Officer [F/O] was flying the aircraft and I was concerned with a cell that had been on the field and at the time was located at the boundary of the airport. I had looked at the F/O's radios and had seen the proper inbound course dialed in and a frequency of 110-something. Before we got to the initial approach fix, the Approach Controller told us to turn right 20 degrees and intercept the 9R localizer. It was at this time I real ized that my F/O had tuned in 110.3 instead of 110.9, the localizer for 9R. We had initially been on the localizer for 9L. For tunately, approaches were not being made on that runway at the time. I think a major contributing factor to this incident is the fact that both localizer frequencies for landing in the same direction start with 110 (110.9 for 9R and 110.3 for 9L). Interestingly enough, both localizer frequencies landing to the west start with 109 (109.1 for 27R and 109.5 for 27L). Our reporter wrote that he had never previously encountered this situation. However, a cursory look through the approach plates for a number of major metropolitan airports revealed quite a few instances in which parallel runway ILS frequencies are similar. Some parallel runway ILS frequencies have the same first three digits, and only the decimal digits differ: 33R/L 11R/L 8R/L 111.95/111.7 110.3/110.7 109.9/109.3 Baltimore-Washington Int’l Minneapolis-St. Paul Atlanta
From Angels to GRUMPs
CALLBACK’s readers occasionally like to embellish on stories and safety tips offered here, and this was the case with our De cember ‘94 issue (#187), which inspired several letters of interest. In response to our “Guardian Angels” item about a Cherokee Six internal fuel drain actuator that was accidentally activated by a passenger, one pilot shared this more uplifting experience:
✍ I owned a converted Twin Comanche. I had been to Florida,
from where I filed IFR in lousy weather back to North Carolina. Level, at altitude and in clouds, I shifted to the outboard tanks, and shortly thereafter the right engine went dead, windmilling. The fuel gauge showed a full tank. I shifted back to the main tanks, and the engine started up again. During the preflight I had drained a not insignificant amount of water from the right outboard tank (there had been heavy rains in Florida and I had never learned that I should have exchanged the short neck gas caps for the tighter long neck). So I decided to switch back to the outboard tank and then pull the fuel drain which fortunately is inside the cockpit. I didn’t have to drain for long before the engine again was running as it should. Inboard fuel drains can save the day... Several readers responded to our article on “GUMP,” offering their own variations on this familiar acronym. First, from a pilot who advocates GRUMP:
One ILS frequency was found with identical decimal digits, and nearly identical first three digits: 2R/C 111.75/110.75 Nashville, TN
Dallas-Ft. Worth has an interesting situation with its parallel cluster “Right” ILS runways assigned the same first three digits, and its parallel cluster “Left” ILS runways also assigned the same first three digits:
✍ Somewhere in my past, someone recommended adding an “R” for Radio, making it GRUMP...particularly when flying VFR from a field using the CTAF to another [field] which uses a different CTAF frequency. [In these situations] it is easy to forget that all the chatter coming over the radio is not on the [frequency] you need. At controlled fields it is less likely that the radio will be mistuned, however frequency changes are easy to miss.
Another correspondent likes GUMPS–with the “S” standing for “Seatbelt.”
ASRS Recently Issued Alerts On...
Spoiler delamination visible only inflight on a B737-500 Alleged design flaw in an L-1011 fuel shutoff switch guard Questionable ATC sequencing of a B-727 behind a B-757 Flight/ground crew illness attributed to rain repellent leak Inadequate length Flight Attendant seatbelts on a DC9-30
A Monthly Safety Bulletin from The Office of the NASA
Aviation Safety Reporting
System,
P.O. Box 189,
Moffett Field, CA
94035-0189
December 1994 Report Intake
Air Carrier Pilots General Aviation Pilots Controllers Cabin/Mechanics/Military/Other 1980 630 70 27
TOTAL
2707
飞行翻译公司 www.aviation.cn 本文链接地址：美国ASRS安全公告CALLBACK cb_189.pdf
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