Number 218
August 1997
Clearance Clarification
Information found in both written and verbal clearances is frequently subject to misinterpretation. In our first ASRS report, instructions in a published procedure were treated as a clearance by a corporate crew. planning purposes. “Expect” altitudes are not considered crossing restrictions until verbally issued by ATC. Another crew fell victim to an apparent readback/hearback error, which resulted in confusion about the clearance, and ultimately, to inadequate separation from another aircraft.
s We were cleared for the VOR arrival. We were at FL310 and had already programmed the “expect-crossingaltitude” of 17,000 feet at the VOR [according to the published arrival procedure]. When the altitude alerter sounded, I advised Center that we were leaving FL310. He acknowledged with a “Roger.” At FL270, Center quizzed us about our descent. I told him we were descending so as to cross the VOR at 17,000 feet. He advised us that we did not have clearance to descend. What we thought was a clearance was in fact an “expect” clearance.
We are both experienced pilots…which just means that experience is no substitute for a direct question to Center when you are in doubt about a clearance. Also, the term “Roger” only means that he received the transmission, not that he understood the transmission. The Aeronautical Information Manual (AIM) Section 5-4-1 indicates that “Expect” altitudes are published for
s Departing IFR, clearance was to maintain 5,000 feet,
expect 12,000 in ten minutes. After hand-off to Center...we understood and read back, “Leaving 5,000 turn left heading 240º for vector on course.” First Officer turned to assigned heading climbing through 5,000 feet. At 5,300 feet Center advised assigned altitude was 5,000 feet. We immediately descended to 5,000. Center then informed us we had traffic at 12 o’clock and a mile at 6,000. After passing traffic, a higher altitude was assigned and climb resumed. In the cockpit, the words “reaching” and “leaving” sound much alike. We now believe the clearance was probably “reaching 5,000, etc.” Even our readback to the controller with “leaving” didn’t catch the different wording. “Reaching” and “leaving” are commonly used ATC terms having different usages. They may be used in clearances involving climbs, descents, turns, or speed changes.
Eye on the Sky
An air taxi pilot credits ATC with a “save”—and his ADF needle with a lesson about weather-induced effects:
ASRS Recently Issued Alerts On...
False GPWS alert attributed to an altimeter error SAAB 340B dual engine failure of unknown cause False FMS alerts following an MD-88 engine failure G2B pressurization failure due to anti-ice duct malfunction A320 flight display failure following an Air Data Recorder fault
A Monthly Safety Bulletin from The Office of the NASA Aviation Safety Reporting System, P.O. Box 189, Moffett Field, CA 94035-0189 http://olias.arc.nasa.gov/asrs
June 1997 Report Intake
Air Carrier Pilots General Aviation Pilots Controllers Cabin/Mechanics/Military/Other 1952 718 88 66
TOTAL
21
24
W
Contributing factors: Static (weather-induced) interference on the ADF needle, and the ILS and DME outof-service. Many thanks to the effort of the controllers. Nice to know they keep an eye on those in the sky.
A cross-check of other available navigational aids might have given the crew contradictory information, motivating them to seek clarification from ATC.
33
s On a deadhead leg, I had received the assigned heading to intercept the final approach for a straight-in NDB approach. Upon turning final, the controller told me to switch to Tower. At that moment the ADF needle quickly began to fall and I reported my position to the Tower as being over the final approach fix. The Tower then cleared me to land and I started my descent to MDA. I had descended 200 feet when I noticed my ADF needle was now pointing toward the nose of the airplane. I immediately leveled off and the Tower advised me to contact Approach. The Approach Controller advised me I was left of course and that the minimum altitude was 2,100 feet. He gave me a heading to re-establish me on final. I climbed from 1,900 feet to 2,100 feet and was switched back to the Tower Controller. This time I had true station passage and started my descent to MDA and completed the approach with no further problems.
Before the advent of on-board weather radar systems, pilots flying near an area of thunderstorm activity would tune their ADFs to a low frequency and watch where the needle pointed. They avoided areas where the needle pointed (indicating thunderstorm-induced static). ATC also kept an eye on an air carrier crew, who almost followed their ADF needle to the wrong airport.
s Cleared for the visual approach at XYZ. All navaids
were tuned and idented for XYZ. I observed bright runway lights with proper orientation. A quick glance at the map display and needle point on the ADF suggested that it was the right airport. The First Officer agreed. We descended to approximately 400 feet when XYZ Tower advised us that we were on final for ABC [about 3 miles short of XYZ]. We initiated a go-around. The ABC runway lights loomed bright and clear with proper orientation. XYZ lights were not as obvious.
3
6
E
12
N
15
30
2824
S
飞行翻译公司 www.aviation.cn 本文链接地址：美国ASRS安全公告CALLBACK cb_218.pdf
August 1997
Clearance Clarification
Information found in both written and verbal clearances is frequently subject to misinterpretation. In our first ASRS report, instructions in a published procedure were treated as a clearance by a corporate crew. planning purposes. “Expect” altitudes are not considered crossing restrictions until verbally issued by ATC. Another crew fell victim to an apparent readback/hearback error, which resulted in confusion about the clearance, and ultimately, to inadequate separation from another aircraft.
s We were cleared for the VOR arrival. We were at FL310 and had already programmed the “expect-crossingaltitude” of 17,000 feet at the VOR [according to the published arrival procedure]. When the altitude alerter sounded, I advised Center that we were leaving FL310. He acknowledged with a “Roger.” At FL270, Center quizzed us about our descent. I told him we were descending so as to cross the VOR at 17,000 feet. He advised us that we did not have clearance to descend. What we thought was a clearance was in fact an “expect” clearance.
We are both experienced pilots…which just means that experience is no substitute for a direct question to Center when you are in doubt about a clearance. Also, the term “Roger” only means that he received the transmission, not that he understood the transmission. The Aeronautical Information Manual (AIM) Section 5-4-1 indicates that “Expect” altitudes are published for
s Departing IFR, clearance was to maintain 5,000 feet,
expect 12,000 in ten minutes. After hand-off to Center...we understood and read back, “Leaving 5,000 turn left heading 240º for vector on course.” First Officer turned to assigned heading climbing through 5,000 feet. At 5,300 feet Center advised assigned altitude was 5,000 feet. We immediately descended to 5,000. Center then informed us we had traffic at 12 o’clock and a mile at 6,000. After passing traffic, a higher altitude was assigned and climb resumed. In the cockpit, the words “reaching” and “leaving” sound much alike. We now believe the clearance was probably “reaching 5,000, etc.” Even our readback to the controller with “leaving” didn’t catch the different wording. “Reaching” and “leaving” are commonly used ATC terms having different usages. They may be used in clearances involving climbs, descents, turns, or speed changes.
Eye on the Sky
An air taxi pilot credits ATC with a “save”—and his ADF needle with a lesson about weather-induced effects:
ASRS Recently Issued Alerts On...
False GPWS alert attributed to an altimeter error SAAB 340B dual engine failure of unknown cause False FMS alerts following an MD-88 engine failure G2B pressurization failure due to anti-ice duct malfunction A320 flight display failure following an Air Data Recorder fault
A Monthly Safety Bulletin from The Office of the NASA Aviation Safety Reporting System, P.O. Box 189, Moffett Field, CA 94035-0189 http://olias.arc.nasa.gov/asrs
June 1997 Report Intake
Air Carrier Pilots General Aviation Pilots Controllers Cabin/Mechanics/Military/Other 1952 718 88 66
TOTAL
21
24
W
Contributing factors: Static (weather-induced) interference on the ADF needle, and the ILS and DME outof-service. Many thanks to the effort of the controllers. Nice to know they keep an eye on those in the sky.
A cross-check of other available navigational aids might have given the crew contradictory information, motivating them to seek clarification from ATC.
33
s On a deadhead leg, I had received the assigned heading to intercept the final approach for a straight-in NDB approach. Upon turning final, the controller told me to switch to Tower. At that moment the ADF needle quickly began to fall and I reported my position to the Tower as being over the final approach fix. The Tower then cleared me to land and I started my descent to MDA. I had descended 200 feet when I noticed my ADF needle was now pointing toward the nose of the airplane. I immediately leveled off and the Tower advised me to contact Approach. The Approach Controller advised me I was left of course and that the minimum altitude was 2,100 feet. He gave me a heading to re-establish me on final. I climbed from 1,900 feet to 2,100 feet and was switched back to the Tower Controller. This time I had true station passage and started my descent to MDA and completed the approach with no further problems.
Before the advent of on-board weather radar systems, pilots flying near an area of thunderstorm activity would tune their ADFs to a low frequency and watch where the needle pointed. They avoided areas where the needle pointed (indicating thunderstorm-induced static). ATC also kept an eye on an air carrier crew, who almost followed their ADF needle to the wrong airport.
s Cleared for the visual approach at XYZ. All navaids
were tuned and idented for XYZ. I observed bright runway lights with proper orientation. A quick glance at the map display and needle point on the ADF suggested that it was the right airport. The First Officer agreed. We descended to approximately 400 feet when XYZ Tower advised us that we were on final for ABC [about 3 miles short of XYZ]. We initiated a go-around. The ABC runway lights loomed bright and clear with proper orientation. XYZ lights were not as obvious.
3
6
E
12
N
15
30
2824
S
飞行翻译公司 www.aviation.cn 本文链接地址：美国ASRS安全公告CALLBACK cb_218.pdf
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