Sunday, March 15, 2009

Hold Everything, Part II

Barnburner 123, hold East of the Sacramento VORTAC on the 080 radial, 4 mile legs, left turns, maintain 5000, expect further clearance in 40 minutes.

In this hypothetical example you'll see that entering a hold involves just a few basic tasks:
  • Fly to the holding fix
  • Cross the fix
  • Turn outbound in the appropriate direction.
  • After a minute (or a minute and a half above 14,000') or the specified DME leg length, turn inbound.
  • Rinse and repeat
The heading you turn to after crossing the holding fix depends on your orientation to the outbound leg, but it is crucial that you know the outbound course. If you are flying a hold that is part of a published procedure, you can just read the outbound course right off the page. If you've been given holding instructions that are not published, start with step 1.

Step 1 - Write down the instructions and read them back
First things first. Don't worry about figuring out the entry at this point, just write the instructions down and confirm with the controller that you've got it right. It helps to know the elements of a holding instruction, the order in which those elements will be given, have a shorthand for recording those instructions, and above all, stay relaxed and ahead of the game. If the controller tells you they have holding instructions and you're not ready to copy, tell them to standby until you are ready.

Taken in order, a holding instruction should contain:
  • Cardinal direction of the OUTBOUND leg (North, NE, E, SE, S, SW, W or NW)
  • Holding fix (a VOR, NDB, intersection, or GPS waypoint)
  • Radial, course, bearing, airway, or route
  • Optional leg length in miles (if not specified, 1 minute legs, 1.5 minute legs above 14,000' MSL)
  • Optional left turns (right turns assumed if this is omitted)
  • Time to expect further clearance (usually to leave the holding pattern)

Here's how it might look after you've recorded these holding instructions.

Step 2 - Fly to the Holding Fix

If the holding fix is a VOR or an NDB, this is basic radio navigation that any proficient instrument pilot should be able to do while half asleep. Come to think of it, when I worked as a freight dog I often felt like I was half asleep!

If the holding fix is the current GPS waypoint, you best press the OBS button to suspend waypoint sequencing.

Within a few miles of the holding fix, begin slowing to your holding speed.

Step 3 Determine the Outbound Course

This step is crucial and there are a few questions you need to ask to determine the outbound course:

Does the cardinal direction (N, NE, E, SE ...) match the radial or bearing?
  • If YES, the radial or bearing is the outbound course.
  • If NO, the reciprocal of the radial or bearing is the outbound course.
A quick way to compute the reciprocal of a radial is to add 200 to the radial and subtract 20 or, subtract 200 and add 20. Most people find this to be easier than trying to add or subtract 180.

In this example the radial and the cardinal direction match so the outbound course is 080 degrees.

Step 4 Write down the Outbound Course

Don't leave this to chance! In a high workload moment, you may forget, then get flummoxed and blow the hold entry.


Step 5 Determine the Holding Pattern Entry

I've illustrated the next step using a G1000 HSI set to GPS, but the same technique applies to a course deviation indicator set to a VOR.

If the direction of turns wasn't specified, right turns are implied, so place your right thumb at the three o'clock position on the heading indicator or the HSI.



If left turns were specified, place your left thumb at the nine o'clock position on the heading indicator or the HSI.



Either way, your thumb should block out about 20 degrees above the three o'clock or nine o'clock position on the HSI (or CDI).

Imagine a horizontal-ish line from the top edge of your thumb that travels through the center of the HSI or heading indicator to the other side. Imagine a vertical line from the center of the HSI or heading indicator up to the twelve o'clock position.

Next, locate the OUTBOUND course you determined in step 3 on the HSI or heading indicator.

Direct Entry
If the OUTBOUND course is located on the HSI below the imaginary horizontal-ish line, do a direct entry .

Fly to the fix and turn in the specified direction to the OUTBOUND course. After a minute (or minute and a half above 14,000') or the specified leg length, turn in the specified direction back to intercept the inbound course.

Teardrop Entry
If the OUTBOUND course is located between the vertical line and your thumb, do a teardrop entry.

The initial outbound heading for a teardrop entry requires just a bit more math.

Start with the outbound course you determined above and think LARS: Left turns, Add 30 degrees, Right turns, Subtract 30 degrees to get your initial teardrop outbound heading and write it down. Crossing the holding fix, turn to the teardop outbound heading. After a minute (or minute and a half above 14,000') or the specified leg length, turn in the specified direction back to intercept the inbound course.

Parallel Entry
If the OUTBOUND course is located between the imaginary horizontal-ish line and the imaginary vertical line, do a parallel entry. In the example above, a parallel entry would be appropriate for entering the hold at Sacramento.

Fly to the fix, turn to the outbound course, and track outbound on the inbound course. After a minute (or minute and a half above 14,000') or the specified leg length, turn OPPOSITE the specified direction back to intercept the inbound course. You will need a pretty aggressive intercept angle (35 to 45 degrees) to intercept the inbound course before reaching the holding fix. After crossing the holding fix, all turns will be in the direction specified in the holding instruction.


Looks like there are a few more details to cover, so stay tuned for part III.

4 comments:

gp said...

Rather than writing "EFC 40 min" when you transcribe a clearance, I find it much nicer to write down the actual time when you can expect further clearance (e.g. 0548Z). It removes a potential "oops." To go a step further, you could also read back the clearance that way: "further clearance at zero five four eight Zulu," which gives the controller a bit more of a chance to catch an error.

John said...

Some controllers will give you a Zulu time and sometimes they'll give you some number of minutes to expect further clearance. The section on holding in Order 7110.65S: Air Traffic Control doesn't even mention EFC times, let alone specify whether they should be given as Zulu times or some number of minutes.

If the controller specifies an EFC time as some number of minutes, you want to do the math and read back a Zulu time, I don't see any harm in it. Paraphrasing the EFC time might reduce the likelihood of a "hear-back" error.

I think for many aspiring instrument pilots, doing this extra step only increases their workload and makes determining the hold entry and flying the hold more difficult.

In the real world of holding, there is usually a periodic give and take between pilot and controller about how much longer they must continue to hold.

Anonymous said...

On many approach charts, the missed approach segment is on the outbound course for the missed approach hold. If you look at the diagram that puts it on the edge of the teardrop/parallel entry sectors. Is there a preferred way to enter the missed approach hold in this situation?

John said...

Excellent question! I'll cover that in Part III.