Light Gun Signals Color and type of signal Aircraft on the ground Aircraft in flight Steady green Steady red Flashing red Alternating red and green Cleared for takeoff Stop Taxi clear of the runway in use Exercise extreme caution Cleared to land Give way to other aircraft and continue circling Airport unsafe, do not land Exercise extreme caution Figure 5-18.  Light gun signals. Example: “Huntsville Approach, balloon 903 Hotel Delta,  at 3,000.” The approach control facility (in this example, Huntsville  Approach) will either reply by saying, “Aircraft calling  Huntsville Approach, standby”, in which case the balloon  pilot does not have a clearance to enter the airspace; or,  approach will reply, saying “Balloon 903 Hotel Delta,  Huntsville, standby.” In this case, the aircraft call sign  was used, and the pilot may enter the airspace. Further  communication may continue until the balloon has either  landed or cleared the airspace. Many balloon pilots fly for years without using a radio of any  kind. Using an aircraft radio is not a difficult task, and, with  practice, can provide a more enjoyable flight. Most ATCs  express an interest in balloons, and go out of their way to  assist balloon pilots in accomplishing their flight safely.  At first glance, the NAS appears to be a complex arena  in which to operate such a simple aircraft. This chapter  simplifies the airspace to the reader, and makes it readily  apparent that it is possible to operate a hot air balloon safely,  without causing conflict. Simple courtesy and common sense goes a long way in  airspace operations. A complete and thorough understanding  of the airspace, combined with good decision-making, will  allow the pilot to do what he or she wishes, with recognition  of the needs of other users of the sky.  In the event that radio communication has failed, or that no  radio is available in the balloon, and continued flight into  the immediate vicinity of an towered airport facility cannot  be avoided, control towers have a “light gun” available.  This device, which looks like an oversized flare gun, allows  tower personnel to “shoot” a directed beam of light at an  approaching aircraft, and may signal field availability options  to the approaching balloon.  [Figure 5-16] Chapter Summary 5-11