Quick answer
Rook Endgame Checking Distance is an endgame technique: Lucena bridge-building. Work from the first evidence position for Rook Endgame Checking Distance, and begin by testing Ra8.
Begin from Ra8 in 6k1/r7/B1K5/R7/8/8/8/8 b - - 4 3. Count the material, king routes, promotion squares and reserve tempi before applying a theoretical rule. The evidence answer is: Rook Endgame Checking Distance: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Ra8 Kc5.
In the Rook Endgame Checking Distance example, notice: side Black; pieces Black king g8, Black rook a7, White bishop a6, White king c6, White rook a5; legal first moves Kh8, Kh7, Kg7, Kf7, Kf8, Ra8, Rb7, Rc7+. Anchor your reading to the FEN above; the inventory is illustrative, not a portable law of chess.
Material and result question
The first evidence board tests Lucena bridge-building; the second board tests Lucena bridge-building. A is seeded by the moves direct FEN setup. B is seeded by direct FEN setup. Related definitions sit in the Chess Wiki and the Endgames hub. Then compare Material Values with Opposite Side King Activity, Endgame Move Order Decisions, Simplifying Into A Favorable Endgame around the side-to-move tempo.
The two inventories make the distinction concrete. A contains side Black; pieces Black king g8, Black rook a7, White bishop a6, White king c6, White rook a5; legal first moves Kh8, Kh7, Kg7, Kf7, Kf8, Ra8, Rb7, Rc7+; B contains side White; pieces Black king h8, White pawn c7, White king c6, Black rook b3, White rook c1; legal first moves c8=N, c8=B, c8=R+, c8=Q+, Kd7, Kd6, Kd5, Kc5. Compare the side to move before comparing the labels in the context of a reserve pawn move.
Topic dossier for this page and board pair r1:6k1 | r2:r7 | r3:B1K5 | r4:R7 | r5:8 | r6:8 | r7:8 | r8:8 / r1:7k | r2:2P5 | r3:2K5 | r4:8 | r5:8 | r6:1r6 | r7:8 | r8:2R5: start with the side-to-move tempo; then test a reserve pawn move; keep the active rook before the pawn push separate from the conversion move order; use an outside passer used as a decoy as the transfer check; and reserve the defender's only active counterplay for the exception.
Conversion or defense plan
On the first board, calculate Ra8 Kc5 after Ra8 and write down the opponent's best reply around the side-to-move tempo. On the second board, calculate Kc5 after Kc5 and check a reserve pawn move. Separate the practical conversion question from the result question; side to move and one checking distance can change the conclusion. In this case the useful condition is the defender's only active counterplay.
Key claim: Rook Endgame Checking Distance is illustrated here by Lucena bridge-building; the first concrete test is Ra8. The board anchor is 6k1/r7/B1K5/R7/8/8/8/8; the example is intentionally narrower than the topic label and should not be generalised without checking the surrounding position..
Practical boundary: To answer “What exact king, pawn, and move-order conditions decide rook endgame checking distance, and how should each side play them?”, compare the recorded setup with Kc5 and the opponent's reply. The decision is useful only when the stated condition survives that concrete test on board 7k/2P5/2K5/8/8/1r6/8/2R5. The evidence records No tablebase outcome is asserted by this generated record; verify the exact FEN before publication and the second board signature r1:7k | r2:2P5 | r3:2K5 | r4:8 | r5:8 | r6:1r6 | r7:8 | r8:2R5. The false-positive test is whether the active rook before the pawn push appears without the conversion move order, so the conclusion is useful only when the stated condition survives that concrete test.
Evidence positions
example-1: Lucena bridge-building
Show answer
Rook Endgame Checking Distance: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Ra8 Kc5.
Why this position is here: Rook Endgame Checking Distance is represented by Lucena bridge-building. This is a direct FEN setup with board anchor 6k1/r7/B1K5/R7/8/8/8/8; no opening history is inferred from the diagram.
FEN: 6k1/r7/B1K5/R7/8/8/8/8 b - - 4 3
Question: What is the first concrete decision in this rook endgame checking distance position?
Answer cue: Rook Endgame Checking Distance: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Ra8 Kc5. The first candidate to test is Ra8. Replay Ra8 Kc5 on board anchor 6k1/r7/B1K5/R7/8/8/8/8 and write down what changes after it.
Evidence boundary: No tablebase outcome is asserted by this generated record; verify the exact FEN before publication.
example-2: Lucena bridge-building
Show answer
Rook Endgame Checking Distance: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Kc5.
Why this position is here: Rook Endgame Checking Distance is represented by Lucena bridge-building. This is a direct FEN setup with board anchor 7k/2P5/2K5/8/8/1r6/8/2R5; no opening history is inferred from the diagram.
FEN: 7k/2P5/2K5/8/8/1r6/8/2R5 w - - 4 3
Question: What is the first concrete decision in this rook endgame checking distance position?
Answer cue: Rook Endgame Checking Distance: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Kc5. The first candidate to test is Kc5. Replay Kc5 on board anchor 7k/2P5/2K5/8/8/1r6/8/2R5 and write down what changes after it.
Evidence boundary: No tablebase outcome is asserted by this generated record; verify the exact FEN before publication.
example-3: Lucena bridge-building
Show answer
Rook Endgame Checking Distance: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: c8=Q.
Why this position is here: Rook Endgame Checking Distance is represented by Lucena bridge-building. This is a direct FEN setup with board anchor 5r1k/1KP5/8/8/8/8/8/5R2; no opening history is inferred from the diagram.
FEN: 5r1k/1KP5/8/8/8/8/8/5R2 w - - 6 4
Question: What is the first concrete decision in this rook endgame checking distance position?
Answer cue: Rook Endgame Checking Distance: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: c8=Q. The first candidate to test is c8=Q. Replay c8=Q on board anchor 5r1k/1KP5/8/8/8/8/8/5R2 and write down what changes after it.
Evidence boundary: No tablebase outcome is asserted by this generated record; verify the exact FEN before publication.
Reading the line
Read the first example (id example-1) as a complete record: continuation Ra8 Kc5, source tablebase. This is a direct FEN setup with board anchor 6k1/r7/B1K5/R7/8/8/8/8; no opening history is inferred from the diagram. If A does not expose Lucena bridge-building, correct the evidence before relying on the prose.
Read the second example (id example-2) separately: continuation Kc5, source tablebase. Its feature is Lucena bridge-building; inventory side White; pieces Black king h8, White pawn c7, White king c6, Black rook b3, White rook c1; legal first moves c8=N, c8=B, c8=R+, c8=Q+, Kd7, Kd6, Kd5, Kc5. Compare what changes between Ra8 and Kc5.
Boundary cases
The main mistake to avoid with Rook Endgame Checking Distance is applying a remembered endgame rule while ignoring side to move, king placement or an unverified result. In A, the missing condition must be located in r1:6k1 | r2:r7 | r3:B1K5 | r4:R7 | r5:8 | r6:8 | r7:8 | r8:8 after Ra8; in B, test it against r1:7k | r2:2P5 | r3:2K5 | r4:8 | r5:8 | r6:1r6 | r7:8 | r8:2R5 after Kc5.
For Rook Endgame Checking Distance, the first board's evidence boundary (after Ra8) is No tablebase outcome is asserted by this generated record; verify the exact FEN before publication. The second board's evidence boundary for Rook Endgame Checking Distance is No tablebase outcome is asserted by this generated record; verify the exact FEN before publication. If a trusted source or careful calculation changes the conclusion around an outside passer used as a decoy, update both the evidence record and this article.
Practice from a real game
play the position for both sides, record the critical tempo, and verify the exact FEN against the cited tablebase before publication. Start with A's side to move and r1:6k1 | r2:r7 | r3:B1K5 | r4:R7 | r5:8 | r6:8 | r7:8 | r8:8; record two candidates, the reply to Ra8 Kc5 and the correction. Repeat with B's side to move and r1:7k | r2:2P5 | r3:2K5 | r4:8 | r5:8 | r6:1r6 | r7:8 | r8:2R5; the changed board tests transfer rather than diagram memory.
After the drill, compare your notes with Opposite Side King Activity, Endgame Move Order Decisions, Simplifying Into A Favorable Endgame through the conversion move order. Keep A's rejected alternative beside B's chosen line Kc5; this shows whether the conclusion survived a new board signature.
Sources and scope
Sources for Rook Endgame Checking Distance: Syzygy tablebase verification reference, 1chess.online editorial scope. Source ids are tablebase, original-analysis. Primary evidence hook: tablebase. Comparisons and practice notes are editorial. Evidence revision: 2026-08-remediation-r2.
Scope note for board pair r1:6k1 | r2:r7 | r3:B1K5 | r4:R7 | r5:8 | r6:8 | r7:8 | r8:8 / r1:7k | r2:2P5 | r3:2K5 | r4:8 | r5:8 | r6:1r6 | r7:8 | r8:2R5: this page does not claim that Ra8 Kc5 is an engine principal variation, that an exact endgame result is verified when the evidence says it is not, or that a tool output replaces human calculation. The conclusion is limited to the recorded boundary and the exception the active rook before the pawn push.