What is best effort ?

Understanding “Best Effort” Satellite Services in Aviation: What Happens When the Network Gets Busy?

As satellite internet services like Starlink enter the aviation market, airlines and passengers are encountering a term familiar to IT professionals but often misunderstood by the broader audience: “best effort” service. Understanding what this means—and how it affects your in-flight connectivity—is crucial as we embrace this new technology.

What Does “Best Effort” Actually Mean?

In networking, “best effort” describes a service model where the provider makes no guarantees about bandwidth, latency, or reliability. The network will try its best to deliver your data, but it doesn’t promise specific performance levels.

Think of it like a highway system. Traditional dedicated satellite services are like having a reserved lane—your bandwidth is guaranteed regardless of traffic. Best effort services are like sharing all lanes with everyone else. When traffic is light, you cruise along at high speed. During rush hour, everyone slows down together.

This is fundamentally different from traditional aviation connectivity services (like Inmarsat or Iridium) that reserved dedicated bandwidth for each aircraft, ensuring predictable performance regardless of how many other planes were online.

The Shared Bandwidth Reality

Here’s the technical reality: each satellite beam has a finite amount of bandwidth—let’s say 20 Gbps as a working example. This capacity must be shared among everyone in that coverage area, which might include:

• 10-20 equipped aircraft
• Hundreds of residential users on the ground
• Maritime and mobile ground terminals
• Business customers

The mathematics are straightforward but sobering. If you have 20 Gbps shared among 500 active users, and the system allocates bandwidth fairly, each user gets approximately 40 Mbps. If that number climbs to 1,000 users, everyone drops to 20 Mbps. At 2,000 concurrent users, it’s down to 10 Mbps per user.

For an aircraft with 200 passengers, that shared allocation must be further divided among everyone streaming, browsing, and working online.

What Happens When the Service Gets Busy?

Contention—the competition for limited network resources—creates several observable effects:

Throughput Degradation: This is the most obvious impact. During peak hours or over busy routes, your available bandwidth drops proportionally to the number of active users. A passenger who enjoyed 5 Mbps during a quiet morning flight might see this drop to 1-2 Mbps during an evening transatlantic crossing when multiple aircraft converge on the same route.

Increased Latency: As more users compete for bandwidth, data packets queue up waiting for transmission. This queuing delay adds to the inherent satellite latency (20-40ms for LEO satellites). Under heavy load, round-trip times can balloon to 200-300ms or more, making video calls jerky and web browsing sluggish.

Variable Performance: Unlike your home internet where performance is relatively consistent, satellite connectivity varies dramatically based on factors beyond your control—your route, the time of day, how many other aircraft are nearby, and ground user activity below you.

Application Impact: Different applications tolerate contention differently. Email and web browsing remain functional at lower speeds, though slower. Video streaming may automatically downgrade quality or buffer frequently. Video conferencing and VoIP calls become increasingly difficult as latency rises. Large file downloads simply take longer.

The Aviation-Specific Challenge

Aviation adds unique complications to the best-effort model:

Route Hotspots: Commercial aviation isn’t randomly distributed. Hundreds of flights funnel through narrow North Atlantic tracks, busy transcontinental corridors, and approach paths to major hubs. When multiple equipped aircraft converge in the same satellite beam simultaneously—which happens regularly on popular routes—contention intensifies.

Predictable Peak Periods: Passenger usage follows patterns. Everyone wants connectivity during cruise phase on long-haul flights. Transatlantic evening eastbound flights all occur at similar times. These predictable peaks create recurring congestion that’s difficult to mitigate.

No User Awareness: Unlike terrestrial networks where users develop intuition about when service is congested, airline passengers have no visibility into how many aircraft are sharing their beam or what ground activity looks like below.

Real-World Performance Expectations

What should airlines and passengers actually expect? Based on current deployments and network modeling:

Best Case Scenario: Off-peak hours, uncongested routes, favorable satellite geometry—users might see 5-10 Mbps per device, with latency in the 30-50ms range. This supports HD streaming and video calls.

Typical Scenario: Moderate congestion on popular routes during normal hours—2-5 Mbps per device, latency 50-100ms. Adequate for SD streaming, web browsing, and most productivity applications.

Congested Scenario: Peak hours on heavily trafficked routes with multiple aircraft in the same beam—1-2 Mbps per device or less, latency exceeding 150ms. Streaming may buffer, video calls struggle, but email and basic browsing remain functional.

Worst Case: Extreme congestion during satellite handoffs or coverage gaps—intermittent connectivity, speeds below 1 Mbps, connection drops. This is relatively rare but possible.

Implications for Airlines and Passengers

Airlines marketing “high-speed satellite internet” need to set realistic expectations. Unlike gate-to-gate promises, best-effort services mean connectivity quality varies flight-to-flight and even minute-to-minute.

For operational use—electronic flight bags, aircraft health monitoring, weather updates—airlines must account for this variability in their system designs. Critical applications may require fallback options or must be designed to tolerate degraded bandwidth.

Passengers accustomed to reliable terrestrial internet will need to adjust expectations. The service works, often quite well, but it’s not a perfect replacement for ground-based connectivity.

Looking Forward

As satellite constellations add capacity through additional satellites and improved ground infrastructure, contention effects should moderate. However, demand typically scales with capacity. As more aircraft equip with satellite terminals and passenger expectations rise, the fundamental best-effort dynamics remain.

The key is understanding what you’re buying. Best effort isn’t inferior—it’s simply a different service model optimized for cost and flexibility rather than guaranteed performance. For aviation connectivity, where some access is vastly better than none, it represents a remarkable technological achievement.

But when your video call drops during that critical meeting over the Atlantic, now you’ll understand why. You’re not experiencing a failure—you’re experiencing the predictable mathematics of shared bandwidth in a best-effort network.

The author specializes in aviation connectivity systems and satellite communications architecture. experiences