1 0 4 Signaling Helicopt er with Mirr or Smok e Fire On bright da ys smok e is more no ticeable than fre while on dull da ys or in twilight the re v er se applies Smok e dissipat es q uickly in a str ong wind and a small fre is useless in these conditions K eep green boughs a v ailable t o creat e smok e on a w ell established fre Three fres about 2030 me tres apar t at the apices of a triangle are an int ernational distress signal and should be used only in an appr opriat e emergency F or practical pur poses a single column of smok e is as ef f ectiv e and is far easier t o maintain Signal Co de Pre vi ously recommended gr oundt oair signal codes using visual elements laid out on the gr ound are so rarely used that the cr yptic messages are unlik ely t o be recognized b y current pilo ts and are no longer recommended f or communication pur poses These ma y be useful t o attract att ention if y ou are lost or stranded but during Sear ch and R escue it is im por tant t o use a v arie ty of w a ys t o attract att ention t o y our self P or tab le VHF T ransceiv er s T w o types of VHF handheld radios are a v ailable f or air t ogr ound communications One lessf amiliar type mak es use of the VHF AM radio syst em installed in all air craf t These radios are used in all air por t air t ogr ound and air t oair communications