As the Second Galactic Civil War escalated, the Rebel Alliance found itself in need of a capable long-range reconnaissance vessel. Strapped for credits, rebel engineers decided to repurpose the reliable Y-Wing platform, eventually resulting in the BTL-A4 Y-Wing "Longprobe". The BTL-A4 is essentially a stripped-down variant of the more common BTL-S3 model, with the weapons systems and most of the heavy hull armor removed. The copilot's seat was taken out to make space for the enhanced life support systems necessary for the ship's intended longer voyages. The starfighter's sensor system was augmented with top-of-the-line components, increasing the ship's scanning ability by eight hundred percent. The overall net loss in mass also boosted its maximum sublight speed in the vacuum of space, allowing the Longprobe to keep pace with most other ships of its class.

However ingenious the design might have been, the BTL-A4 was only in production for three standard years, with manufacturing being discontinued shortly after the establishment of the New Republic in Year 8. While the Longprobe performed admirably, increased military budgets allowed the New Republic to use faster and better armed ships like the RZ-1 "A-Wing" for reconnaissance and scouting missions, leaving the Longprobe to be eventually relegated to hyperlane prospecting missions. Once the current fleet size had been deemed adequate for its use, the New Republic retired the variant. Today, the few BTL-A4's that have found their way onto the public market through surplus sales or theft have become highly sought after vessels. While nearly two decades old, the Longprobe's sensor capabilities are still unsurpassed, matched only by the Imperial TIE/sr, and the abundance of spare parts for its sister variants makes the BTL-A4 surprisingly easy to maintain for a ship as rare as it is.