The Unexpected Results of The "Expect" Clearance Technique

Issue Number 4 : June 1993

The Unexpected Results of the "Expect" Clearance Technique

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.

Background

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.

Expect-actions

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. . . . .

What are the Problems?

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.

Situation #1

Altitude Deviation, Less Than Standard Separation:

"...[Air carrier] X west bound through my sector at flight level 370 and...[light transport] Y on the FEVER 2 STAR to SDL... Y was issued a descent to flight level 390 and the pilot asked if the descent was at his discretion. I told him affirmative, however to expect to cross FEVER Intersection at 11,000 [feet] and 250K. The...[flight crew] misunderstood my expect for a clearance and started descent, ...[and passed through flight level 390] resulting in a loss of separation."

Supplemental Information from ACN 127770:

"[Air carrier] X noticed an aircraft on descent through our altitude in front of us...Y was in a rapid rate of descent. ATC indicated...Y was descending into Scottsdale, and was cleared to descend from flight level 450 to flight level 390 and to expect further descent." (ACN 128222, 127770)

Analysis

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.

Situation # 2

Speed Deviation:

"Both the Co-pilot and I misread the GLAND SIX Arrival chart as 'expect clearance to cross GLAND at 10,000 feet and 250 knots.' Actually, it said 'Cross GLAND at 250 knots, expect clearance to cross at 10,000 feet.' When we were cleared to cross GLAND at 10,000 feet, we discussed the clearance and decided that, since the Controller did not give a speed restriction, none was required. We were [then] switched from Center to Approach at GLAND. The [Approach] Controller asked our airspeed and we told him it was 290 knots. He said it should have been 250 knots, since that was a 'mandatory,' not an 'expect,' restriction. He said the slower speed was important for vectoring onto the approach. It is difficult to read small print on approach charts. Pilots anticipate mandatory restrictions only on profile descent charts. You see what you expect to see. Speed restriction [was] not given by [the] Controller when 10,000 foot altitude restriction given, since it was on the chart. I recommend an underline, shadow, or some other highlight for mandatory altitude or airspeed restrictions on non-profile charts. Controllers should restate mandatory airspeed restrictions when altitude restriction is transmitted." [Emphasis added] (ACN 137454)

Analysis

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.

Situation # 3

Altitude Deviation, Potential Traffic Conflict:

"Positioned north of airport and heading approximately 230 degrees, on approach to...6R. Controller asked if we could accept visual to 6R. We accepted and were told to descend to 4000 feet (on current heading) and to report runway in sight. I called runway in sight out of 5000 feet while approaching 4000 feet; however, the radio call was delayed due to another transmission from Approach. Continuing descent, at about 3300 feet, we told Approach we had the runway as the frequency became clear. The Controller advised [to] maintain 4000 feet, climb back to 4000 feet, which we did. It became known to me then that we had not been cleared for the visual as I had thought."

Supplemental Information from ACN 133419

"...Approach said, 'Cleared to 4000 feet, expect visual, report runway in sight.' I called out 4000 feet, as I could see we had a sink rate. At 3800 feet, Captain had gear down, flaps 5 degrees...and I said, 'We're cleared to 4000 feet'...Approach said, 'I show you at 3800 feet, check altimeter 29.69. You have traffic at 3000 feet.' We continued descent to 3500 feet. I told [the] Captain, 'We're at 3500 feet, we have traffic at 3000 feet, we're cleared to 4000 feet.' He said, 'Tell them we have the runway in sight for a visual.' When I told [the] Controller we had runway in sight, he said, 'You have traffic at 3000 feet, climb immediately to 4000 feet.' I said, 'We're at 3300 feet, climbing to 4000 feet.' We then climbed to 4000 feet and had a normal approach and landing." (ACN 133416, 133419)

Analysis

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.

Situation # 4

Runway Transgression:

"While holding short of Runway 17R at DFW, The Tower Controller was busy. Both the First Officer and I understood him to say position and hold behind...air carrier [X]. He was extremely busy giving continuous run-on instructions with no gap to allow for acknowledgments. After I taxied into position, the Tower Controller said, 'Now you are cleared into position and hold -- I told you to expect position and hold behind...air carrier [X].' We stated we heard we were cleared into position. He then responded with 'I'll pull the tape.' Regardless of who was correct here, this was a prime example of poor communication...the clearance was ambiguous and obviously easy to misinterpret." [Emphasis added] (ACN 179906)

Analysis

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.

Situation # 5

Altitude Deviation:

"The First Officer was flying the aircraft. We normally cruise at 18,000 feet on this route, but due to winds aloft and weather conditions, we decided on 12,000 feet for a final cruise altitude. We were handed off to...Center while climbing through approximately 5000 feet. After checking in, our clearance was to 11,000 feet and we were told to 'expect 12,000 feet.' Climbing at roughly 1200 feet per minute, I (the PNF) selected 11,000 feet on the altitude alerter. Through 10,000 feet I performed the '10,000/Climbing' checklist and began to activate our anti-ice equipment, as we were entering an area of probable icing. Upon level-off, I noticed we were at 12,000 feet, and not 11,000 feet. As I was about to inform [the] Center [Controller], he called and cleared us to 12,000 feet. I acknowledged and nothing was said about the matter between us and [the] Center. I looked at the altitude alerter and discovered that it had been reset to 12,000 feet by the First Officer (who was also flying the airplane). I explained to him that we were told to 'expect' 12,000 feet and that we were only cleared to 11,000 feet, which is why I set the altitude alerter to 11,000 feet. He told me that he thought we were cleared to 12,000 feet and (since I was busy with the checklists and anti-ice equipment) he reset the alerter to 12,000 feet. Our 1000 foot deviation was the result." (ACN 164511)

Analysis

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.

Factors

Communications

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).

Other Factors

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.

The Problem

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.

The Cure

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.

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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