Figure: G450 EVS Takeoff Presentation, from Eddie's aircraft.

Eddie Sez:

It is easy to ignore the HUD on takeoff, in fact that is how we start our HUD existence, ignoring it and slowly learning how to use it to our advantage. Perhaps we can bypass the ignoring stage with a few pointers.

The photo above, as it says, is from the EVS but the display is the same. We tend to focus on the flight path vector and the flight director diamond, but what do we usually worry about during a takeoff without a HUD? Yup, you should add that speed error tape to your crosscheck.

If you are new to this, you might want to watch this short one-minute video showing a takeoff using the EVS: EVS vs. Visual (Takeoff). (Keep an eye on that speed error tape.)

What follows are quotes from the references listed below, but most of this is pure technique, shown in blue.

Set Up

Figure: G450 HUD takeoff set up, from Eddie's notes.

Just as with the PFD, setting the guidance panel with HDG, the heading bug on runway heading, and selecting TO/GA will get you the HDG, TO, TO on the top row of the HUD display. The airspeed should be at the 40 KCAS peg with V2 bugged and indicated above the speed dial.

Unlike the conventional PFD:

  • The local horizon on the HUD will appear to be at the end of the runway. The PFD has a horizon line of sorts that will be below this.
  • The flight path vector will be right on the local horizon, since that is where the aircraft is headed prior to rotation. The PFD display will be well below this.
  • The boresight will be below the local horizon. The PFD aircraft reference symbol points to the same position.
  • The flight director diamond will be slightly above the local horizon. The PFD will be much higher.

The speed error tape should be rather long off the left wing of the flight path vector and there should be three tick marks in the correct order: V1, VR, and V2. The instantaneous speed carat will be at the wing tip when stationary and should immediately jump up as the aircraft accelerates. More about these below: Speed Error Tape.

The bottom of the display will have a conventional CDI until you get within 12° of the runway centerline, at which point it becomes conformal. More about this below: Conformal Lateral Deviation Indicator, Scale, Centerline.


Figure: G450 HUD takeoff 60 KCAS, from Eddie's notes.

As you accelerate, the speed error tape gets shorter. At 60 KCAS the vertical mode indicator — the second item on the top line of the display — should change from TO to HOLD, which flashes for five seconds before boxing.

As long as the Display Controller HUD menu is set for the CDI in the AUTO mode, you should have a conformal CDI on the bottom of the display. (When you are within 12° of the course, the CDI/HSI selection does not matter when in AUTO.) The book says the CDI will be based on RNP at this point, which is more than likely 1.0 nm. As you can see from the photo on the top of this page, this does not appear to be true. More about this below: Conformal Lateral Deviation Indicator, Scale, Centerline.


Figure: G450 HUD rotation, from Eddie's notes.

As you rotate the boresight will go from below the local horizon and pass to above the flight path vector where it should remain for the rest of the flight until after landing touchdown. You will likely out climb the local horizon which may disappear off the bottom of the display. You will attempt to bring the flight path vector over the flight director diamond. Depending on altitude of the initial level off altitude, you may immediately get an ASEL indication next to the autothrottle flight director annunciator.

Unless you have selected CAGED mode, the flight path vector will probably move left or right away from the relative wind.

Initial Climb

As you continue your initial climb:

Symbology Notes

Extracted from: G450 Normal Procedures & Techniques / HUD - Symbology.

Conformal Lateral Deviation Indicator, Scale, Centerline

Figure: G450 HUD Conformal Lateral Deviation Indicator, from Eddie's notes.

[G450 Aircraft Operating Manual, §2B-18-10, ¶2, page 26.] The [Conformal Lateral Deviation Scale] is described for various navigation sources in [the table below]. The centerline is the indicator of aircraft position along the lateral deviation scale.

Deviation VOR/TACAN LOC/MLS FMS 1/2/3 FMS 1/2/3 APP
2nd dot right 10° 5 NM Based on RNP
1st dot right 2.5 NM Based on RNP
Center 0 NM Based on RNP
1st dot left 2.5 NM Based on RNP
2nd dot left 10° 5 NM Based on RNP

To see a conformal lateral deviation display like this, you need to select LSK 5R AUTO from the display controller HUD menu. Once you are within 12° of course the HSI or CDI displayed (depending on LSK 4R) will switch to the conformal display.

Figure: G450 Display Controller HUD Page, from Eddie's notes.

[G450 Aircraft Operating Manual, §2B-18-10, ¶6, page 9.] Pushing [the LSK 5L] key scrolls through AUTO, ON, and OFF. This key selects the lateral display format from one of the following HUD displays:

  • HSI
  • CDI
  • Conformal lateral deviation
  • Non-conformal deviation.

AUTO -- Selects one of three positions, and the effect of the selected position depends on whether the CDI or the HSI is selected. [The table below] describes this key selection relative to the selected display.

ON -- Selects full HSI or CDI display format depending on what was selected on LSK 4L.

OFF -- Results in a non-conformal CDI display only.

  Course Select/Desired Track Error < 12° Course Select/Desired Track Error > 12°
AUTO Conformal only Full HSI or CDI (Note 1)
ON Full HSI or CDI (Note 1) Full HSI or CDI (Note 1)
OFF Non-conformal CDI only Non-conformal CDI only
1. Depends on the selection made with the HSI/CDI line select key.
2. For a typical ILS approach, select AUTO and CDI. As the localizer
moves to less than 12°, the display automatically switches to the
conformal CDI display if it was not previously selected.
3. The power-up setting is the combination set when the aircraft was
last powered-down.

[G450 Aircraft Operating Manual, §2B-18-10, ¶6, page 8.] When the AUTO has been selected ON, pushing the CDI/HSI key toggles HUD display between the CDI display and the HSI display format.

Speed Error Tape

Figure: G450 HUD Instantaneous Acceleration Caret and Speed Error Tape, from Eddie's notes.

[G450 Aircraft Operating Manual, §2B-18-20, ¶2.A., page 21.]

  • This tape rises or descends from the left wing of the FPV. It represents the difference between the selected airspeed and the current airspeed. If the tape is below the wing, current airspeed is less than the selected airspeed. If the current airspeed is greater than the selected airspeed, the tape is above the wing. The tape is designed so that if the speed error tape is not displayed, the selected airspeed is being maintained.
  • If V1, VR, or V2 are within the range of the speed error tape, they are displayed to the left of the speed error tape. The indicator moves vertically along the speed error tape, so that the distance between the FPV wing and the VSPEED indicator is proportional to the speed error tape scale. The V1 and VR values are parked at the bottom of the speed error tape if their values place them outside the displayed values on the tape.

Using the speed error tape in conjunction with the instantaneous acceleration caret gives you a wealth of information on the aircraft's energy state:

Figure: G450 HUD Speed Cues, from Eddie's notes.


Gulfstream G450 Aircraft Operating Manual, Revision 35, April 30, 2013.