▁increased ▁hold ▁times , ▁and ▁increased ▁separation ▁between ▁aircraft . ▁ ▁Vari ant ▁ ▁Inst rument ▁guidance ▁system ▁( IG S ) ▁( Local izer ▁type ▁direction al ▁aid ▁( L DA ) ▁in ▁the ▁United ▁States ) ▁– ▁a ▁modified ▁I LS ▁to ▁accommod ate ▁a ▁non - stra ight ▁approach ; ▁the ▁most ▁famous ▁example ▁was ▁for ▁the ▁approach ▁to ▁run way ▁ 1 3 ▁at ▁K ai ▁Tak ▁Airport , ▁Hong ▁Kong . ▁ ▁Ident ification ▁ ▁In ▁addition ▁to ▁the ▁previously ▁mentioned ▁navig ational ▁signals , ▁the ▁local izer ▁provides ▁for ▁I LS ▁facility ▁identification ▁by ▁period ically ▁transm itting ▁a ▁ 1 , 0 2 0   Hz ▁Mor se ▁code ▁identification ▁signal . ▁For ▁example , ▁the ▁I LS ▁for ▁run way ▁ 4 R ▁at ▁John ▁F . ▁Kennedy ▁International ▁Airport ▁transm its ▁I J F K ▁to ▁identify ▁itself , ▁while ▁run way ▁ 4 L ▁is ▁known ▁as ▁I HI Q . ▁This ▁lets ▁users ▁know ▁the ▁facility ▁is ▁operating ▁normally ▁and ▁that ▁they ▁are ▁tun ed ▁to ▁the ▁correct ▁I LS . ▁ ▁The ▁gli de ▁slope ▁station ▁transm its ▁no ▁identification ▁signal , ▁so ▁I LS ▁equipment ▁re lies ▁on ▁the ▁local izer ▁for ▁identification . ▁ ▁Mon itor ing ▁It ▁is ▁essential ▁that ▁any ▁failure ▁of ▁the ▁I LS ▁to ▁provide ▁safe ▁guidance ▁be ▁detected ▁immediately ▁by ▁the ▁pilot . ▁To ▁achieve ▁this , ▁mon itors ▁contin ually ▁assess ▁the ▁vital ▁characteristics ▁of ▁the ▁transm issions . ▁If ▁any ▁significant ▁deviation