A vehicle spotter (civilian term), or ground guide (U.S. military term), is a person who uses hand signals to direct the movement of vehicles when maneuvering in areas such as parking lots and staging areas.

So far, the only national law or regulation specifying spotter signals I've found is the UK's 1996 Health and Safety law No. 341.^[1] See also this. See this for verbal commands for rescue hoisting.

American Society of Agricultural Engineers has developed standardized hand signals.^[2]

The most complete definition of these signals and procedures can be found in:these U.S. Military manuals:

GTA 17-02-091:Visual Signals Armor Fighting Vehicle (flipbook); conflicts with Enform signals
FM 17-19 (July 1982):
FM 21-60: Visual Signals (chapter 2) http://www.apd.army.mil/
TC 3-21.60: Visual Signals (supersedes FM 21-60)
AR 385-10, The Army Safety Program (Chap. 11--10. Army combat vehicle safety guidelines (mentions ground guides only)
AR 385-55: Prevention of Motor Vehicle Accidents (mentions ground guides; shows no signals)
FM 21-306: Manual for the Track Combat Vehicle Driver
FM 21-305 (Army)/AFMAN 24-306^[3] (Air Force), Manual for the Wheeled Vehicle Driver, which defines "Air Force Standard Spotting Hand and Arm Signals" or Air Force Standardized Basic Hand and Arm Signals (IAW TO 36M-1-141, 463L Material Handling Equipment System)
TC 21-305-20, Manual for the Wheeled Vehicle Operator (Appendix A) https://armypubs.us.army.mil/doctrine/DR_pubs/dr_b/pdf/tc21_305_20.pdf
TC 21--306, Tracked Combat Vehicle Driver Training https://armypubs.us.army.mil/doctrine/DR_pubs/dr_c/pdf/tc21_306.pdf
Principles of Ground Guiding (Video) https://safety.army.mil/MEDIA/VideoLibrary/VideoPlayer/TabId/112/VideoId/23/Ground-Guiding.aspx
Enform: https://www.youtube.com/watch?v=4xQzLwgtb88
Aircraft Signals Natops Manual, NAVAIR 00-80T-113^[4]
- Hand signals Chart 1^[5]
- Hand signals Chart 2^[6]
- Hand signals Chart 3^[7]
Safety Manual for Operating Trucks at Harvests
Directing forklift signals
OSHA 29 CFR 1926, Subpart CC, Appendix A^[8]
Workers Guide to Hand Signals for Directing Vehicles (formerly IRP12 Hand Signals for Directing Vehicles)

The Canadian government organization Enform publishes a similar set of hand and arm signals, Workers Guide to Hand Signals for Directing Vehicles (formerly IRP12 Hand Signals for Directing Vehicles).

The U.S. OSHA also makes similar recommendations for spotting signals^[9]^[10]

Signals

text


	UK H&S Regulation No. 341		Enform
Signal Name	Day Signal	Description	Day Signal	Night Signal	Description
General signals
Start	HSR 1996 IX 3a	Both arms are extended horizontally with the palms facing forwards.
Get driver's attention					point at driver with one arm, and keep pose until he acknowledges
Planned Stop (I like signal from BS 7121: 1989 Code of practice for safe use of cranes best.)^[11]	HSR 1996 IX 3b	The right arm points upwards with the palm facing forwards.			wrists crossed above head
End	HSR 1996 IX 3c	Both hands are clasped at chest height.
Start engine
Stop engine
Lights on					Index finger of both hands pointing towards eyes
Lights off					Index finger of right hand pointing towards eye and "thumbs down" signal with left hand
Clear to leave area					transition from driver's attention signal to pointing both arms in the direction of travel
Acknowledged
I do not understand					Raise both harms sidward to the horozontal, bend both arms at elbows and place both hands across the face, palms to the front.
Vertical movements
Raise	HSR 1996 IX 3d	The right arm points upwards with the palm facing forward and slowly makes a circle.
Lower	HSR 1996 IX 3e	The right arm points downwards with the palm facing inwards and slowly makes a circle.
Vertical distance	HSR 1996 IX 3f	The hands indicate the relevant distance.
Raise ramp?
Lower ramp?
Horizontal movements
Move forwards	HSR 1996 IX 3g	Both arms are bent with the palms facing upwards, and the forearms make slow movements towards the body.
Move backwards	HSR 1996 IX 3h	Both arms are bent with the palms facing downwards, and the forearms make slow movements away from the body.
Turn signal					arms out to both sides, arm on side opposite of turn waving up
Sharp turn/Change direction?					use tracked vehicle signs?
To the spotter's right (to the driver's left)	HSR 1996 IX 3i	The right arm is extended more or less horizontally with the palm facing downwards and slowly makes small movements to the right.
To the spotter's left (to the driver's right)	HSR 1996 IX 3j	The left arm is extended more or less horizontally with the palm facing downwards and slowly makes small movements to the left.
Horizontal distance	HSR 1996 IX 3k	The hands indicate the relevant distance.
Distance to stopping point					put arms above head and gradually move into planned stop signal
Danger
Emergency Stop (I like signal from BS 7121: 1989 Code of practice for safe use of cranes best.)	HSR 1996 IX 3l	Both arms points upwards with the palms facing forwards.			waving and crossing wrists above head
Quick (double-time?)		All movements faster.
Slow		All movements slower.
Proceed Slowly					waving arms up and down with palms facing direction of travel

References

[1] "The Health and Safety (Safety Signs and Signals) Regulations 1996" (PDF).

[2] "Agricultural Hand Signals".

[3] "AFMAN24-306 9 DECEMBER 2016" (PDF).

[4] "Aircraft Signals NATOPS Manual" (PDF).

[5] "Hand Signals Chart 1" (PDF).

[6] "Hand Signals Chart 2" (PDF).

[7] "Hand signals Chart 3" (PDF).

[8] "Cranes & Derricks in Construction".

[9] "Basic Spotter Hand Signals".

[10] "Spotting signals".

[11] "BS 7121: 1989 Code of practice for safe use of cranes" (PDF).

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