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Preparing to Land

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My recent article “Preparing for Flight” was so well received that I’m inspired to shine light on yet another high-workload phase of flight – arrival and landing. As I mentioned in the previous piece, one of the highest times of workload for flight crews occurs at the gate prior to departure. This is a phase of preparation that sets the precedent for a successful flight. However, alongside the intensity of readying for departure, follows an equally demanding phase of arrival, landing, and taxi to the gate. Thorough coordination and communication between the flight crew and ATC, as well as proper follow-through in guiding the aircraft safely during descent and landing is crucial. I’ll initiate this topic from a point just prior to descent.

As the end of the en route phase of flight nears, pilots begin planning for arrival. Many of the busier airports filter arriving aircraft from all different directions by means of standardized arrival procedures. Each pilot carries with them navigation charts for every airport served by their respective airline, and included are all of the possible procedures that ATC may request to be flown. Each of these procedures has a name, for example, the PHLBO arrival procedure that guides aircraft from the southern U.S. into Newark’s Liberty Int’l airport. Not only do these arrival routes guide aircraft laterally to the airport area, but often they contain vertical guidance as well. On the PHLBO procedure for example, there are many points along the route that aircraft are required to cross at a certain altitude. These altitude assignments are called “crossing restrictions” and they help to ease the workload of ATC. Instead of having to instruct each specific aircraft to descend to different altitudes throughout the arrival, ATC can simply instruct pilots to “descend via the PHLBO arrival”. The pilots, aware of their arrival assignment before even leaving the gate, prepare for the arrival prior to initiating it. They will review the instructions of the arrival aloud to form a plan that conforms with the restrictions. The PHLBO arrival requires descending aircraft to meet multiple crossing restrictions. These altitudes are carefully chosen to separate PHLBO flights inbound to Newark from aircraft arriving and departing other airports in the area, such as Philadelphia Int’l, an airport directly underneath the final portion of the PHLBO arrival. The on-board flight management system (FMS) computer mentioned in my previous article is programmed by the pilots with the arrival as well as its many crossing restrictions and in turn directs the pilots via visual cues when to initiate descent to satisfy each altitude requirement. Pilots also use a mental formula as a back up to know when a descent must begin in order to arrive at a certain point at a certain altitude. For example, if a flight is cruising at 35,000’ and needs to cross a point at 25,000’, the altitude to lose is 10,000’. We drop off the last three zeros, leaving 10. This number is multiplied by three, based on a comfortable glide path of three degrees. Such a gradual descent allows your beverage to stay in place on its tray table. Anyway, 10 multiplied by 3 equals 30, which correlates to miles from the point to begin descent. So, 30 miles away we will begin our descent to meet the restriction - clear as mud right?

The first point at which descent begins is called the top-of-descent, or TOD. It’s around this time that we typically make our final passenger address sharing the current weather, estimated time of arrival, and gate of arrival. How do we know this information? Most commercial aircraft are equipped with an on board communications computer that pilots use to send and receive information from the airport or airline. Crews can request a weather report from most airports to be “e-mailed” to the flight deck. The current weather, runways in use, and pertinent airport notes such as taxiway closures are included in the message. A similar message is sent regarding arrival gate information. We even have the ability via this system to notify the airport folks, for example, if a customer will require a wheelchair upon arrival. This same system allows pilots to communicate with maintenance or dispatch should it be necessary while in flight. The FMS also generates an estimated time of arrival that we refer to in our passenger announcement. All of this computerized information is available by radio in the event of a computer failure.

As the aircraft nears the end of the arrival procedure, ATC then “vectors” aircraft for approach to the runway. Vectoring is a term given to the lateral directions provided by ATC. In terms of expected time, this is the most un-predictable phase of flight. If the airspace is quiet, ATC will more or less guide flights directly to the runway. On the other hand, if the skies are crowded, aircraft are often vectored all over the place, sometimes even away from the runway. ATC will furthermore issue speed reductions and lower altitudes as flights near the airport and one another. It comes down to arranging aircraft that are arriving from different directions into a single line-up to the runway. It’s organized chaos at times and what could be a 5-minute direct course to the runway can otherwise quickly become 30 minutes. The phrase “so close, yet so far” comes to mind in these situations! On clear nights, pilots can actually see the line up of aircraft in front of them as a trail of lights. Seeing this makes it almost predictable when ATC will instruct the next turn to commence to keep aligned in the queue.

Once aligned with the runway, pilots guide their aircraft for landing either visually or by means of an instrument approach. During times of low visibility, most runways are equipped with a system called an ILS (instrument landing system) that transmits signals to aircraft in order to guide them both laterally and vertically to the landing zone. These signals allow flight crews to follow on board instrumentation that guides them to a safe landing. The system is so accurate, that many aircraft are capable of landing with zero-visibility. In these cases, the autopilot will literally land the aircraft via the ILS guidance.

Taxiing to the gate after landing, believe it or not, is equally demanding to all previous phases. At busy airports, especially those with multiple runways being used at the same time, aircraft arrive, depart, and taxi within close proximity. ATC ground control carefully provides taxi instructions to pilots that are meant to keep them on a safe path to the gate. Flight crews and ATC alike must be extremely attentive during ground operations. In the interest of safety, new technologies have recently been introduced to help prevent incursions on the ground. ATC at many airports now has a display that depicts a real-time location of all aircraft on the ground. The system provide an alert if a collision course is detected.

Despite thorough planning and safe execution by your flight crews, a few frustrations will always be imminent. One such annoyance is having to wait for your arriving gate to become available upon landing. Finite gate space is a problem these days with so many scheduled flights. Airline operations does their best to arrange gate assignments based on availability for arriving flights, but if your flight is early, or an aircraft has a maintenance issue that delays its departure at your assigned gate, you’ll be waiting in most cases. As always, thanks for reading and keep a lookout for my bi-weekly contribution.

Daniel Fahl Staff Writer
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psseshadri
Great read!! While for a passenger flying from A to B might sound so simple, the tasks mfor the flying crew outlined in the two articles only make me wonder how complex it actually is. Many thanks.
DanielFahl
Daniel Fahl Staff Writer 4
All, I have received numerous requests for access to my previously submitted articles. I'm providing a link here that when visited, will open a page that allows you to view all of my past articles. Thanks for reaching out!

http://flightaware.com/user/DanielFahl/squawks
jmedina94
Julian Medina 4
Thanks again! Looks like another great read!
nutt507
Pete Morgan 2
Thank you very much, your efforts are much appreciated.
organfreak
Aw man, you can't fool me! I KNOW all y'all have to do is push the 'down' button! :-)
fedexerik
Erik Scott 2
The best summary of a commercial pilot ever!
Yankee1
Robert West 2
I am still confused at the signs along the taxi/runways IE:(LAX) But then PAX don't have the control tower to guide them.
Give me a good old Air Force base. The runways are not tossing and turning up and down or short IE: aircraft carriers.
jim78418
jim78418 2
I find this information fascinating. I once thought I had an idea about what pilots did. I realize I have never had a clue to what goes on behind the door in that space with all the dials, gauges, handles, buttons and lights of different colors. Please keep writing articles about what's going on in the cockpit. Thanks for your effort.
CaryA
Cary Alburn 2
As the occasional "victim" of vectors "all over the place" while anticipating an instrument approach in my own airplane, I've had no trouble understanding delays, but the flying public who isn't so aware definitely can use your explanations. Unfortunately, the biggest complainers about the effect of procedures on their personal situation won't be reading these articles. You can't teach those who refuse to be taught! But I echo other comments, that you've done a masterful job of explaining in non-technicalese what's going on up front and why. Now if you could only force those complainers to read your articles!
Wingscrubber
Wingscrubber 2
Nice explanation. Maybe next you could explain how to interpret IFR approach charts for those of us who are still VFR dummies, like me?
Belton
With a little tightening, these would make great a great series of articles for in-flight magazines or posting on airline websites.

Have always wondered why the airlines don't put more of this kind of "here's how it works" info on their sites. The more the flying public understands about what's happening in the front of the bus, the more likely they will be to accept it when they occasionally get stuck in the "penalty box" waiting for a gate.
jbbooks1
Lewis Tripp 2
I can only fly Microsoft Flight Simulator now. I can fly various different aircraft and someone asked me If I could fly commercial aircraft in an emergency situation. Only if I am the last resort.I pray that everyone with me never has to find out
delayedAgain
delayedAgain 2
A question, do pilots still use the PAPI during landing or do they rely on math and instruments?
RichardSkaggs
Hear! Hear!
DanielFahl
Daniel Fahl Staff Writer 2
If a PAPI or a VASI is available, we use it for guidance whenever visual conditions prevail.
DashTrash
DashTrash 1
Both airlines I flew for required you to back up the VASI / PAPI with electronic guidance as well, but the visual cues are helpful.
LarryQB
LarryQB 1
Yes, the PAPI and its close cousin VASI are helpful in landing large aircraft under any condition... good weather to not-so. An alternative is using the GPS vertical navigation capability, however unless you have a heads up display that involves shifting focus from the instrument panel to the outside several times, thus a PAPI or VASI is easier.

jkudlick
Just think of those signs like the exit signs on the highway.

At least Navy pilots know the runway isn't the same place it was when they left. Air Farce pilots are like bees; if you move the hive, they are lost. ;)

I kid because I respect.
NickLalani
Nick Lalani 1
Loved it.Great article.
vagabond79
Jon Kirby 1
Excellent! Please keep these informative articles coming. They are very interesting for someone like me who has just a general interest in aviation.
SNOWY3034
Excellent article once again. Please let's have more. Thanks.
fg64
Frank Gurnari 1
Great article. Thanks much!
tlmonk
Terry Martin 1
I have listened via scanner to ATC and pilots for 35 yrs. Thanks for your info on landing procedures.
gortmull
Thomas Gorton 1
Daniel, thanks so much for sharing your knowledge in a clear and concise fashion. Have you considered writing a book?
Dhelens
patrick tit 1
A new thank for this so interesting information. Next one?
docroc3
How very impressive. It's not the time for passengers to insist on special attention. What are the cabin crew doling thrlough this phase?
Gasser
Mike Schutz 1
This is a good article with alot of insight for a commercial passenger aircraft during approach Undoubtably, your readers would be even more interested in an article that explains in detail the difference between cargo and passenger aircraft.
rocketperson393
Art Troutman 1
Remember, back in the good old days, when an arriving aircraft would be directed by Approach Control to fly a "racetrack" shaped holding pattern - at a specified altitude at a particular location. Quite often this would be a series of them in a descending "ladder" pattern at a series of descending altitudes. This was more apt to happen at busier airports, during the times of the day when there were more arrivals. Doesn't happen as often anymore - why?

The answer - ATC has come up with an ingenious system of coordinating the arrival patterns so as to forecast or predict these multiple patterns and "dovetail" them with one another, coordinated with takeoffs of departing aircraft.

Ever been aboard a departing flight, taxiing out to the takeoff runway - with no others ahead of your plane - and find that your flight taxis into a holding pad and sits there for quite some time before taking off? Or better yet - lingers at the departure gate, after the door has been closed and the bridge retracted? You guessed it - your flight has been "timed" to mesh with other flights on approach to your destination at the same time. I always appreciate it when an announcement is made from the flight deck over the PA system to explain the reason for this unanticipated delay. If nothing else, this clever system saves a lot of fuel, and is safer to boot.
zaflyer
Ralph Connell 1
Thank You so much. As usual very informative...In particular, the descent rate 'formula' Using Flight Sim....often struggeld with that one!
Pigleta6
Pigleta6 1
One of the items not mentioned is that pilots take a best guess at the arrival runway and approach to program into the FMS. Places like Atlanta have four runways that are used simultaneously for arrivals and departures. If the runway assignment is different from the what is already input into the FMS, this leads to extremely high workload for approximately 5-10 min as the pilots reprogram the FMS make all the appropriate instrument changes (different localized freq, decision heights, etc) and then brief the approach to the different runway... All while descending and complying with the STAR and ATC directions. As the FMS is reprogrammed we also have to be extremely careful not to delete any of the crossing restrictions that may have been input into the "box" as this may lead to altitude deviations and possibly a violation. Busy busy busy. Great article by the way!
Pigleta6
Pigleta6 1
That was supposed to be "localizer" frequency not localized. Darn autocorrect on my iPhone!
Pigleta6
Pigleta6 1
Not exactly... The arrivals from the south usually use rw 10 or 28 unless it is not too busy then 27L or 9R might be used... Haven't figured out how ATC balances flow to the various runways. Most of the time I get it right on what runway and approach will be assigned, but it is occasionally different...
ajames854
ALAN JAMES 1
Thanks for this Daniel. It appears to me landing can be more complex than take-off at busy airports; hence your 'organised chaos' comment.
jpag
Thank you very much for a very informative read
rwf1001
Great stuff-keep these coming!
uncwflying
Don Tait 1
awesome article! i love reading about this stuff!
yukon1
EDWARD moore 1
Once again a great read'' Now i see part of the workload my son goes through.....thanks
AviatorLEO
AviatorLEO 1
Good article, and very informative ;-)
jonnymcbride
On the descent procedure, what is your vertical speed? 1800fpm or what?
w7psk
Ricky Scott 1
As an FMC Systems Engineer, Im loving your article :)
jcarey805
Jeff Carey 1
good article. Thank you.
preacher1
preacher1 1
It is really good to see some technical, yet easy to understand articles, come out that the flying public can understand, and pilots in training/advancing can see what they have to look forward to.lol. Excellent job, as usual, man.
deklerk
Great reading. Thanks for another great read. Looking forward to the next one.
ebc1
Eugene Cross 1
Great writeup! Although I am not a pilot, I am fascinated by aviation and instrument flying. (Live next to KTRI). One question: On the PHLBO plate there are other altitudes listed that are lower than the crossing altitudes (eg. 17000, 10000, etc). They are on the vectors between waypoints. What do these mean?
Regards,
ebc
preacher1
preacher1 1
Just a curious question, kinda off the subject??? Does anybody know why KMEM has been showing up on FA lately under a delay of some type. Anywhere from 30 min to 1 hour. With all the downsizing DAL did since the bought NWA, 3 runways and a ne multimillion$ tower and TRACON. Seems like this has been fairly regular now for about the past month.
pbrzek
JK Bishop 1
Great reading.
Woodman51
Dale Mays 1
Great read for a wannabe like me!
theostavfly
Thanks for this great way of explaining . No more complains when things do not go perfectly. Let's the Angels give you guidance when things are difficult. Regards .
sancollins
sancollins 1
Thanks for walking us through the process. You're abolutely correct... You're not done flying the airplane until its shutdown and secured.
RichardSkaggs
After 4 1/2 years, USAF A/C maintenance worker appreciates your education in general aviation commercial flight procedures. Can now better appreciate pilot's complexities.
Big thanks for posting.
Eglin AFB, Fl.
DashTrash
DashTrash 1
It's not really a guess. We can look at the ATIS through ACARS and know what runway the destination is using anytime during the flight. At places like ATL, arrivals from the north are going to the north runways, arrivals from the south going to the southern runways. You're going to get radar vectors to final and will use green data, so even if you load the wrong approach you're not likely to line up on the wrong runway.

My preference was to get the recent ATIS before top of descent and have the approach loaded / briefed. If there are any changes you generally get them with plenty of time to change the box and re-brief the approach. The only true FMS I've used is the Honeywell FMZ-2000, and approach changes can be made in less than a minute.
mk882004
Matt Kladder 1
Fed ex is still huge there
DanielFahl
Daniel Fahl Staff Writer 1
Those altitudes are MEA's, or Minimum Enroute Altitudes. These are the lowest altitudes in a given segment that assure obstacle clearance and/or navigational signal coverage.
DanielFahl
Daniel Fahl Staff Writer 1
Good question, Jonathan. The descent rate necessary to meet a crossing restriction is based on the speed at which the aircraft is moving across the ground. The FMS automatically computes the necessary vertical speed to conform with any restrictions and in turn displays a visual cue for pilots to follow.

A common mental-math formula we use to back up the FMS data is to multiply the current ground speed x 5 to get vertical speed necessary in FPM. For example, a 500 knot ground speed x 5 = 2,500FPM in order to meet the restriction. This formula is constantly run in the back of our heads, as ground speed changes significantly during descent due to wind velocity and true airspeed variations.

I hope that answers your question.
preacher1
preacher1 1
Well, I know they are; they always have been. I just hadn't heard of them doing any major schedule changes or expansions lately. It's like yesterday evening. They were over an hour for a period of 2-3 hours around 6pm. This morning around 530, they were at 1/2 hour or so and now they are clear. Just seems strange.
jonnymcbride
That does thanks!
kelara27
Really informative - it is so important that passengers listen to the flight crew. Misses the preparing for Flight" article - would like to read same.
Safe Flying