The Art of Sequencing: A Guide to Success
(Note: Tower will be handling all this. You can’t always have approach to help you out… Time to get your hands dirty if things get busy. ^-^)
Sup, guys? Today, we’re going to be looking at one of the absolute essentials of controlling- sequencing. Nowadays, sequencing is of absolute vitality in order to maintain order (see what I did there?) in a cacophony of aircraft chaos. Are you ready to find out what sequencing is all about? Good!
First off, burn this mantra in your head: sequencing is your friend, sequencing is your love, sequencing is your life.
Got that? Great!
What is sequencing?
Sequencing is the act by an air traffic controller of which he or she orders/numbers aircraft in a traffic pattern or numbers aircraft for landing/the option. Sequencing allows pilots to know who they’re supposed to follow when it’s busy or there’s other aircraft coming in for landing or traffic work.
Sequencing is all about common sense. It involves not just the air traffic controller, but the pilot. Here’s why:
-The pilot must be aware of what he or she is supposed to follow in order to prevent jamming up traffic. -The controller must be aware of the number of people in the sequence in order to direct them in safely. -The pilot must exercise safety caution when told which aircraft to follow. -The pilot must be respectful of other aircraft in the sequence. -The controller expects the pilot to follow the sequence in order to get everyone in.
As a controller, you will be able to sequence in a number of ways.
-Sequencing (by itself- controllers may find this button further down the “pattern instructions” list.
*Number 1, 2, 3, etc- traffic to follow is on left/right downwind/base, etc.
-Entry pattern commands (found in the pattern instructions list- entirely separate from the sequencing button, with one exception: sequencing has a built in option in the entry pattern instructions. However, pattern entry commands should only be used when an aircraft has to enter the pattern. There are other uses, but we are focusing this on sequencing.
*Enter left/right downwind/base, etc- number XX- traffic to follow is on XXXXX.
With that down, we’re going to delve into a series of exercises regarding sequencing. Read carefully, and I will be demonstrating various ways on how to sequence.
Exercise 1: 'Dem Counting!
What you see here is a chart of a basic traffic flow into a single runway. In order to exercise our brains and move on to more difficult sequencing aspects later, practice counting! Go ahead and imagine HOW you would count those planes in.
TIP: Pay attention to the traffic at the 45-degree intercept.
If you’ve done so, here’s what the numbered order of planes should look like:
Sequencing is all about counting and paying attention, as demonstrated by our little exercise above.
But wait! What about the guy on the 45-degree intercept?
Fair point. If you’re worried about how that aircraft managed to slide into the pattern all smooth-like, here are a few techniques you could do:
-Tell the person entering the pattern to maintain best forward speed. This should allow enough of a speed margin to allow the entering aircraft to enter safely. This is where pilot reliance comes it- it is also up to the pilot to interpret what “maintain best forward speed” means to him or her.
-Tell the guy to his left to make a left/right 360 to allow time for a smooth integration.(However, be warned- ordering an aircraft to do a 360 has a much more susceptible chance of clogging up the traffic pattern if aircraft happen to get TOO close, thus forcing in orders to either maintain slowest practical speed or also to make 360s).
Exercise 2: Double-Trouble
You’re in a tower… and two lanes of traffic on the left and right hand side pop up! (Be aware that this isn’t usually a common scenario while controlling- this is an example of how hectic things can get. I’m a firm believer in preparing for the most intense of things in order to excel at lesser types of pressure while controlling)
Left and RIGHT traffic? What do I do?!?!
First off, stay calm. We can do this.
There are several ways that you could handle this scenario. First off, which traffic pattern do you want to slate off? The left or right? Or do you want to do both?
Here are some helpful commands to help keep the flow moving smoothly:
-I’ll call your base
-Make a left/right 360
-Maintain slowest practical/best forward speed
-(To a lesser extend, extend upwind. This is mainly used only for people remaining in the pattern in lieu of departure)
Why are those commands important to sequencing?
Here’s why: they HELP the plane(s) to maintain a proper and safe distance from the aircraft they’re following, which is an essential must. On a lesser scale, a use of those commands could be considered to buy additional time for departing aircraft to get out, in lieu of previous arrivals. Those commands are also used to manage and organize traffic to get in efficiently, without aircraft crashing into each other and making a mess out of your beautiful sequencing.
Now that we’ve got this information down, you have a couple of options to handle this. One scenario you could do is choose which hand traffic gets to go first for landing. Left or right? Your choice.
What’s going to happen?
Good point. I will now be demonstrating the “extend downwind” command as an aspect of helping you to clear the maze of aircraft flying around.
In the picture above, you can see the use of extend downwind on the first aircraft on the right hand traffic pattern. This allows the pilot to understand that they MUST fly downwind further than they would wish, in order to compensate time for other traffic to do whatever it is that they’re doing.
Why are we using “extend downwind” in this scenario?
That’s an excellent point. There are various reasons as to why “extend downwind” could be used in this scenario, which would differ from controller to controller. Here’s several aspects of why:
- You want to buy additional time to get as many departures out as possible.
- You want more time to assess the situation.
- You want maximum safety between the eventual merging of both traffic patterns.
Here’s another thing that could be done- the continuous merging of traffic by using the “I’ll call your base” command.
Here, you can use “I’ll call your base” to handle the traffic flow in two ways:
-Allow the aircraft from either the left/right traffic hand to go first.
-Create a “stack” effect by funneling in both left and right traffic patterns into final at the same time. This has the unfortunate side effect of severely limiting outbound departures, however.
But… wait… why aren’t we addressing sequencing?
That’s a good question. This exercise serves to show you the commands used in tandem with sequencing- not the dilly-dally numbers only, which was covered in Exercise One.
That’s it for exercise two! This exercise serves to educate you on the importance of USING commands to help your sequencing. Exercise one serves to educate you on counting planes to sequence. Get ready for exercise three… which brings both of them together.
Exercise 3: A Global View
Okay, here’s our final exercise. In this rather more confusing flow of traffic, let us apply what we have learned. In the image above, consider the elongated rectangle as the runway, and the circles as planes. We will be using the east-to-west flow as the active runway. This exercise serves to purpose what could be considered as a highly-pressurized situation. You may not even see dual-traffic circumstances while controlling at all.
Whoa! Looks really complicated and messy, right? Never fear, we will straighten this out! First off, take a deep breath.
Start with the process of elimination. Which plane is closest to the runway?
That’s right! The plane directly east of the runway is the closest… The very first command you should be giving it is “enter straight in, runway XX.”
With that done, search for the second plane. In this scenario, I have selected the plane from the northeast corner of the sketch to serve as aircraft number two. The order you should then give regarding its approximate position is “enter right base, runway XX, number 2, traffic to follow is on final.”
Where’s aircraft number three? Search for the third closest plane- in this case, I am using the plane to the approximate southeast position of plane number one. The entry command would then follow as- “enter left base, runway XX, number three, traffic to follow is on right base.” But wait! Things get a tad bit more tricky here. Aircraft number two and three are both about the same distance from the turn onto final… You must now use what you’ve learned earlier- usage of “make a left/right 360” or “maintain slowest practical/best forward speed.” Use them in tandem as you feel is appropriate for the situation.
Next, aircraft number four! In this case, I have selected the closest direct-west aircraft to aircraft number two. The appropriate command for this guy is “enter right downwind, runway XX, number 4, traffic to follow is on left base.” You may want to use a “I’ll call your base” command or “extend downwind” if things get a tad bit hairy with conflict between those two planes.
Aircraft number five! This is where things start to get even trickier. As you can see, the aircraft directly south of aircraft number four is a tad bit closer than the aircraft to the west of number four. I will be using the south aircraft as aircraft number five. The entry command for this scenario would be- “enter left downwind, runway XX, number 5, traffic to follow is on right downwind.” Use the learned extensions of managing sequencing as appropriate.
Halfway Point (For those of you who are getting confused)
Time to push on to number six… I will be using the aircraft directly a tad bit west of aircraft number four as number six. The entry command should follow as- “enter right downwind, runway XX, number 6, traffic to follow is on left downwind.” Exercise your “sequencing helpers” as I call them.
Number seven! We’re getting close! Let’s search for good 'ol seven… Here, I will be using the aircraft to the west of number five as number seven. The entry instruction will serve as- “enter left downwind, runway XX, number 7, traffic to follow is on right downwind.”
Lucky number eight! Personally, this is my favorite and luckiest number at all, so let’s get cracking! If you’ve been following closely, I would select the aircraft directly to the west of number seven as number eight. The command would follow as- “enter left downwind, runway XX, number 8, traffic to follow is on left downwind.”
Nine-nine-niner-time! Direct your attention to the cluster of two aircraft at the northwest corner of the sketch. Those are the final dudes we need to get in… Here, you have two options- left or right downwind? In this case, I will be using right downwind. Entry is- “enter right downwind, runway XX, number 9, traffic to follow is on left downwind.” Use your sequencing helpers!
At last… number ten! I bet you all know where ten is by now… The very northwestern circle. Let’s wrap things up by having him follow number nine as instructed- “enter right downwind, runway XX, number 10, traffic to follow is on right downwind.”
Finally! All that is over!
Well, that’s sequencing wrapped up in a nutshell! I hope that this guide helps aspiring controllers to reach the advanced ranks… Above all, I hope that each and every one of you thoroughly enjoys what this guide has to offer! Stay safe, and happy controlling!
(P.S- @Swang007- If you can move this to the tutorials section, it would be much appreciated.)