Okay, your pilots are determined by your choice of weither to embark on the MSF, NESF, Triada, Inoco, or Alex mission lines...

These are the pilots you will get no matter what:
Hero
Ternie
Greyhair
Kalem
Joseph - He temporarily joins your party for the artifact expedition, and leaves after that.

If you go NESF (going to the mercenary base), you will get:
Che - You get him when you have to fight off a massive pirate fleet while doing one of Alexandra's missions.
Alexandra - Shes the one who comes to the rescue you after you rescue Ternie

If you go MSF (going to the Patrol headquarters), you will get:
Validol - You get an optional mission to find him, I recommend you take it.
Viper - Shes the one who rescues you after you rescue Ternie
Adm. Trump - If you decide to side with Trump rather than Viper, Viper leaves and you get Trump in her place

If you go Triada (going to the Triada Headquarters), you will probably get (I never played the Triada line, so I donno):
Aja
Alice

If you go Inoco (Betraying triada after given the option by Inoco), which you probably wont because its so badly bugged:
Jana
SAM

If you go Alex (if you fail a mission):
Alex
Cleric

I played NESF, Alex, and MSF Campaigns and did not lose Ternie in any of them...

You probably mean greyhair... there is no such thing as a pilot named silverlight.

Thanks Master Nanaki. Would you mind telling me when I will have pilots after Greyhair?

Depends which mission line you pick.

Nanaki,

I will go with MSF

MSF... After your first mission with them (where you have to plant a bomb on a station), you have the option of either going to someone's friend, or doing the second mission. Choose the former, and you will acquire Validol.

After that, you generally do not get any additional people until you rescue Ternie and Kalem, than you also get Viper.

If you side with Admiral Trump when Viper tries to arrest him, than he will replace Viper on your team.

Any info on the recruitable pilot classes? Here's what I know from playing the NESF route and a bit of Triada Route:

Hero - Pilot/Gunner/Missile Gunner/Systems Engineer
Ternie - Gunner with Laser Proficiency, Precursor Summoning and Berserker & Precursor Tech Adaptation.
Greyhair - Gunner with Heavy Cannon Proficiency
Kalem - Systems Engineer with Machine Gun Proficiency
Joseph - Missile Gunner & System Engineer with Heavy Cannon Proficiency also with Berserker, Alien & Precursor Tech Adaptation.
Che - Pilot with Heavy Cannon Proficiency
Alexandra - Pilot with Heavy Cannon Proficiency & NESF Summoning ability
Alice - Missile Gunner with Machine Gun Proficiency
Aja - Pilot & Gunner with Heavy Cannon Proficiency
Validol - Missile Gunner
Viper - Pilot with MSF Summoning ability
Adm. Trump - Pilot with MSF Summoning ability
Jana - Haven't tried the InoCo route yet
SAM - Haven't tried the InoCo route yet
Alex - Haven't tried Alex's route yet
Cleric - Haven't tried Alex's route yet

Credit goes to Nanaki & valky for info on Aja, Validol, Trump and Viper.

Validol is very missile oriented, and Adm Trump and Viper are both very similar to eachother and are both focused on piloting with MSF Summoning ability.

That means Trump, Viper and Alexandra are similar. They focus on piloting and can summon reinforcements from their factions. Thanks, Nanaki.

Aja is focused on piloting too and can fly all ships up to rank 5 if you get her (already unlocked).
But she has yet (just saved Ternie) no summoning ability.. s*cks :evil:

Aja also focuses on passive Gunnery skill with Heavy Cannons Proficiency. Thanks for the info, valky.