AEROGRAPHER'S MATE 3 & 2 



<r^ 





CEILING = BASELINE x 



TANGENT OF \ 



CLINOMETER ANGLE \ 



+ HEIGHT OF BASELINE \ 



ABOVE SEA LEVEL \ 



BASELINE 

 (FIXED KNOWN DISTANCE] 



CEILING LIGHT 

 PROJECTOR OR 

 SEARCH LIGHT 



CLINOMETER 

 ML- 591/U 



/////////////////////////M^ 



Figure 5-7. — Obtaining cloud base height with Clinometer ML-591/U. 



209.113 



Check the clinometer for damage, wear, 

 and corrosion. Maintenance is limited to clean- 

 ing, minor repair, replacement of damaged or 

 worn parts, and adjustment. Instructions for 

 major repairs and for disassembly are covered 

 in the technical manual pertaining to this equip- 

 ment. 



CLOUD HEIGHT SET AN/GMQ-13( ) 



The cloud height set is used on relatively 

 short baselines of 400 to 900 feet, with the 

 result that the highest accurate value of cloud 

 height measurement is approximately 5,000 feet. 

 The standard baseline is 400 feet. Cloud heights 



can be quite accurately measured in the height 

 range of interest to pilots during final approach. 



The cloud height set system was designed 

 to give frequent measurements from a remote 

 location. It is used primarily at the end of an 

 instrument runway. 



Operational efficiency of the equipment is 

 influenced by several factors, such as possible 

 interference by radio transmitters, vibration 

 from various sources, strong induction fields, 

 or proximity of high- intensity lamps having a 

 high percent of modulation. 



From an observational standpoint it is de- 

 sirable to install the equipment in the approach 

 zone of the most commonly used instrument 

 runway near the middle marker. 



86 



