Issue Number 4 : June 1993
by Don George
I'm getting ready for another flight on an air carrier, and these somber events never fail to generate a lot of thought about some of the problems in our National Airspace System. I am somewhat familiar with these problems because I've been involved with the analysis of incident reports submitted to the NASA Aviation Safety Reporting System (ASRS) over the past sixteen years, and I'm happy to say that you folks, the users of the airspace, do a fine job of keeping ASRS apprised of the types of problems being encountered.
For this upcoming flight I will once again be acting as PIC on a non-stop (hopefully), coast-to-coast wide-body aircraft. PIC, in my case, means either Passenger in Coach, or Prisoner in Coach, depending upon my attitude of the day. I take the responsibilities of PIC very seriously and always start flight planning several weeks, or sometimes months, in advance. Part of the preflight planning includes the selection of a "Primary Worry of the Day," along with several secondary or alternate problems to worry about. For this trip I have chosen the subject of "expect" clearances as the primary.
Most pilots and controllers are familiar with the term expect clearance, but it seems to me that the term is a real misnomer, because what is referred to as expect clearance is not an Air Traffic Control (ATC) clearance at all, and should never be thought of as an authorization to do something -- except in some rare cases of loss of radio communication.
For the remainder of this article I will try very hard to refrain from putting the words expect and clearance together in that order; expect should not be used as an adjective to describe a type of clearance. Okay, I expect you get the idea.
When used in the proper circumstances, expressed correctly by the controller and understood by the pilots, the ATC technique of telling the pilots what to expect is a very good method for making the ATC system work better and for easing both cockpit and controller workload. The word expect is one of the planning tools which controllers can use very effectively to smooth out the flow of air traffic. However, as with most tools, there are some precautions which perhaps should be "printed on the container," or in some manner brought to the attention of the users.
This article is an attempt to provide some of those cautions, and also to offer some suggestions to make the "expect" technique safer and more effective.
Once upon a time, on a dark and stormy night, in an effort to assist pilots and controllers in their planning, the phraseology "...Expect altitude XXX, or Flight Level XXX in YY minutes/miles..." was introduced into the Controllers Handbook (ATP 7110.65). The intent was to allow the pilot to better plan climb/descent profiles. Although well intended, this practice contributed to a large number of altitude deviations.
The climb/descent phases of flight are quite busy times in the life of a flight crew, and the work load in a single-pilot cockpit may be even more critical. During those times when cockpit duties require that one pilot is responsible for flying, communicating, and possibly configuring the aircraft for climb or descent, it is easy for the pilot to misunderstand an instruction to expect an altitude change. Further, these phases of flight usually occur in airspace where controllers are often very busy, and the potential seriousness of the problem is increased if the controller fails to detect an error in the readback -- a traffic conflict may well be the result.
Whenever a pilot requests an altitude change, or if the controller wishes to alert the pilot that a new altitude assignment will be forthcoming, the controller often uses the terminology, "Expect [specific altitude] in XX minutes/in YY miles/ at [fix]/after passing [traffic], or after [meeting some other condition]."
The ASRS database contains many reports of pilots misinterpreting this type of transmission as being a clearance to climb/descend to the specific altitude mentioned.
The problem has been alleviated to some degree by a change in the ATP 7110.65 Handbook. Paragraph 4-46 now enables the controller to inform an aircraft when to expect climb or descent clearance without stating a specific altitude. The phraseology now reads, "EXPECT HIGHER/LOWER ALTITUDE IN (numbers of miles or minutes) MILES/MINUTES." Nonetheless, "expect" type deviations continue to occur because some controllers are not aware of, or have forgotten it.
I have always preached that controllers should not mention an altitude to a pilot unless they want the pilot to go there, so I believe that this newer handbook phraseology is a big step in the right direction, and should decrease the number of altitude deviations. However, in addition to the climb/descent phases of flight, the "expect" technique is used in conjunction with all sorts of down-line planning. Some common examples include: expect vectors; expect visual approach; expect ILS Runway two-seven; expect departure after two more landings; expect no delay; expect (altitude) ten minutes after departure; expect to hold at; and the list goes on and on.
In addition to the verbal transmissions of what pilots may expect, there are also visual "transmissions" placed on charts for planning purposes. Standard Terminal Arrivals (STARs) and Standard Instrument Departures (SIDs) very often include expected altitudes, expected course guidance, expected speeds, etc. Here again, remember that the printing of those expect values on the charts does not constitute an ATC clearance to descend, climb, turn, etc. If the chart says expect, the pilot still needs a specific clearance from the controller before the action is authorized. However, when the altitudes, routes, speeds, etc., are printed without the word expect, they are mandatory. Profile descent procedures contain good examples of these mandatory crossing altitudes and tracks to be flown, and do not seem to cause nearly as many problems as do the STARs and SIDs. Probably the STARs/SIDs are more often confused because they may contain both mandatory and expect values.
All of this sounds pretty straight forward and fairly uncomplicated, so. . . . .
Well, reports to the ASRS reflect a variety of incident types in which there was an unexpected action resulting from the use of the "expect" technique. In the preparation of this article I started with several hundred such reports in front of me, and after reading them several times, I have picked a few which may provide you with some insight into the kinds of problems being encountered -- kind of like trying to pick the best six or seven chunks of apple from a barrel of fruit salad.
Learning from other peoples' mistakes sure beats the heck out of making your own errors, so it should prove to be beneficial for you to read, interpret and analyze the following reports submitted to ASRS. I suggest that you take the report narratives one at a time, and try to figure out what happened, why it happened, and what, if anything, should have been done differently to prevent the occurrence. Compare your analysis to ours.
Supplemental Information from ACN 127770:
If the Controller had delayed any mention of 11,000 feet until the aircraft had passed each other, there probably would have been no incident to report.
The STAR Chart for this arrival has an expect crossing altitude, but airspeed is mandatory -- not an uncommon situation. Perhaps the flight crew did not adequately brief the descent and approach.
Supplemental Information from ACN 133419
One-half of the flight crew understood that the message was an "expect" advisory. Unfortunately, the other half was flying. Better crew coordination and cockpit management was needed here.
During an extremely busy traffic situation, the Controller was trying to keep things moving expeditiously by advising this flight crew of what to expect. However, the flight crew misunderstood the planning advisory to be an actual clearance into position on the runway. Perhaps the use of "Expect Technique" was unnecessary in this situation, and was a contributing factor in the runway incursion incident.
Some of the other factors were: frequency congestion, traffic volume, controller ATC technique, controller radio communication technique, and flight crew anticipation and perception.
There was a breakdown in cockpit coordination. Additionally, the Controller could have said "Expect higher," instead of "Expect 12,000 feet." Hope the reporter gets a chance to read this article.
Space doesn't permit, but I wish that we could have included more ASRS report narratives because, as previously stated, there are important lessons to be learned from other folks' misadventures.
A communication error is the most frequently cited problem element of incidents reported to ASRS, and you probably noted that some type of communication problem played a role in each of the "expect" incidents presented in this article.
Communication problems take a variety of forms. Equipment deficiencies, phraseology, similar callsigns, speech rate, blocked transmissions, and failure of the readback/hearback process are just a few types of communications problems. The subject is too broad to be covered to any great degree in this article, but I do want to make the point that communication problems often lead to a "Flawed Information Transfer" (FIT), and if the flawed information is not corrected soon enough, the result may be an "Occasional Semi-Hysterical Information Transfer" (acronym unknown).
In addition to communications factors, there are other factors which contribute to "expect" incidents. Some are: pilot/controller training in progress, pilot/controller experience level, pilot/controller distractions, pilot/controller work load, weather, fatigue, schedule pressures, cockpit coordination/management, controller planning/technique, charts/publications, traffic volume, etc.
Sometimes very unexpected and undesirable actions are taken by pilots after they have received an "expect" transmission from a controller, or after misinterpreting some "expect" information printed on a chart. The intended transfer of information (verbal or visual) may be misheard, misunderstood, mis-stated, misread, misinterpreted, or simply missed.
|Controllers||Pilots||Pilots and Controllers|
1. Avoid, whenever feasible, issuing specific values (such as altitudes or airspeeds), by instead transmitting phrases like "expect higher altitude," "expect turn shortly," "expect speed reduction prior to (fix)," etc.
2. When using your "expect" technique, try putting a lot of emphasis on the word "expect."
3. Use your "expect" technique in a timely manner (timing is important). For example, it is probably not a good idea to mention an expect altitude at the same time that two aircraft with minimum vertical separation are about to pass each other.
4. Establish a good hearback habit so that flawed information transfer can be corrected during the readback/hearback process -- before an incident occurs.
1. When a controller or a chart says to "expect" something, it means that there is a tentative plan in place, but the pilot should NOT take action until receiving a specific ATC clearance. Keep in mind that the actual clearance may be different from what you had been told to expect because the air traffic situation has changed.
2. Try to give a precise readback as soon as frequency availability permits; always report leaving a previously assigned altitude. Even better, any time an altitude change is about to be made, the pilot should advise ATC of the altitude that is being vacated as well as the intended (target) altitude. For example, aircraft XYZ has just been cleared to descend from flight level 220 to 11,000 feet. Good technique would be for the flight crew to call ATC prior to initiating the descent, saying "ABC (Center), XYZ leaving flight level two-two-zero for one-one thousand, that's eleven thousand."
1. Work to enhance radio communication skills. Adopt the policy of not accepting doubtful messages, and ask for clarification or repeat of any unclear transmissions. Check technique for clear, concise phraseology and acceptable speech rates.
2. Be alert to the possibility of other contributing factors being present. While these other factors may not be directly controllable, it should help if we are aware of the fact that they may be affecting our performance at any given time, and that we must take precautionary steps to minimize their effects. For example, when the flight crew fatigue factor is present, and the flight crew is in a "hurry-up" mode due to schedule pressure -- it is time to take a deep breath and a few extra seconds to check, and then recheck.
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