airmass: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/airmass - from package: munipack

You may install the required package with command yum install {package}

Error in other languages:
airmass: bevel nie gevind nie
airmass: comandă negăsită
airmass: comando não encontrado
airmass: commande introuvable
airmass: command not found
airmass: käsku ei ole
airmass: không tìm thấy lệnh
airmass: komanda nerasta
airmass: Kommando nicht gefunden.
airmass: kommandot finns inte
airmass: komut yok
airmass: nie znaleziono polecenia
airmass: níor aimsíodh an t-ordú
airmass: no se encontró la orden
airmass: no s'ha trobat l'ordre
airmass: opdracht niet gevonden
airmass: parancs nem található
airmass: perintah tidak ditemukan
airmass: príkaz nenájdený
airmass: příkaz nenalezen
airmass: команда не найдена
airmass: командата не е открита
airmass: 命令找不到
airmass: コマンドが見つかりません